Xia1

They do a lot of staggering with releasing decisions, the timeframe is highly variable, it's apparently very hard to get in touch with the department and get a straight answer. Many students find themselves in "limbo", not hearing one way or another if they are accepted or rejected after many others report their own decisions; they sometimes release these decisions after April 15th and some are still yet accepted. So perhaps this means they have a "hidden" waitlist so to speak? In any case, I wouldn't worry about any schools until I got information directly from them informing me of my rejection.

Phone call from out-of-state number. Adrenaline spike. Multi-level marketer.
 

I'll offer any insight I can that may not have been mentioned previously; and take it with a grain of salt, as I'm still in the application process myself! Much of this advice is either personal or gathered from individuals who have been through the process or are involved in the actual admissions themselves.
2) Since you will graduate next winter, I'd say if you start working on your applications now for next season, there's no real reason to take an extra year. If you treat your academics like a full time job, there's no reason you won't have enough time for prep by next winter. I started my writing sample during the summer before my senior year, took two semesters of independent study my senior year to work on it, submitted it as a thesis for some honors requirements, and then took a year off and worked on it more along with prepping for the GRE. During my time off school, I worked/am working 35+ hours a week and had plenty of time to make large revisions to my thesis. If you start now there's no reason you can't have a strong sample by 2019, especially since you'll stay in close contact with professors who can offer advice for revisions. Make no mistake about it, the writing sample is priority number 1 for applications. It's why 170/170 GREs don't guarantee admission to anywhere. A middling sample can't be made up for like middling letters or scores/grades.
3) Grad seminars with good grades always look nice on a transcript. As far as your worries about grades go, just follow this advice: get good grades  in all seriousness though, if you think they will lower your GPA below 3.8, don't take them. Otherwise, I'd take them, and try as hard as you can to get an A- or A.
4) My independent studies appeared on my CV, with when they occurred, who they were under, and what they produced.
5) I'd say only apply to places you are willing to go. If that includes only top 20 schools, so be it. An acceptance to an unranked school means nothing to you if you wouldn't actually like to attend. No shame in that at all. On top of that, I'm convinced anyone with a strong enough sample can make it just about anywhere as long they meet certain very general (but high) benchmarks, which you seem to do. The only advice I could give is prioritize schools strong in your AOI. So if you want to study phil of language, prefer CUNY to Princeton. Maybe. As far as your chances, I think you've definitely got a great start, with good GREs (~90th percentile?) great letters and an amazing sample, you'll definitely make for an above average applicant, though you'll find many above average applicants shut out from year to year. 
6) It's not clear. As long as that person can strongly, individualistically attest to your abilities, their relative fame can only help you. I personally would say that strong letters that single you out as brilliant from relatively unknown professors are vastly preferable to moderate letters from famous professors, U Chicago makes this clear on their page on their admissions process.
7) Most places seem to counteract grade inflation by checking against GRE scores to detect any warning signs, but perceived university difficulty definitely matters.
8) It can only help you, all else being perfect. However, my impression is that university pedigree can't save an application with a humdrum sample and letters.
9) I certainly would include it, but I have no idea if it matters.
10) I included a few non philosophy things on my CV, like volunteer work and where I've been when I'm not at school. Don't see how this really helps or hinders anyone though.
Best of luck!

Hi all, just introducing myself. First time applicant, and anxious as to how this will go. I am applying across the top 50, and am most hopeful about Notre Dame. My greatest weakness is my relative no name undergrad (though a large university), but I was the top (phil) student in my graduating class. I'm sure a certain someone will appear to reinforce how important pedigree is, but alas, I can do nothing to change it now. So I suppose we'll see! Here's hoping, best of luck to all!

I suppose I meant having analytic (in the strictest sense) characteristics rather than the "school of thought" distinction. That is to say, successful samples emphasize clear definitions, carefully constructed premises, and deal in rigorous argumentation; rather than being arcane, imprecise, and needlessly wordy. That these respectively appear to characterize "analytic" and "continental" philosophy is my own interpretation and opinion, I'll gladly admit, and certainly not a necessary set of features for either. Like I said, a paper on mental supervenience that looks like it was written by Heidegger would be less preferable than a paper on phenomenology that looks like it was written by Peter van Inwagen. And I'm certainly not trying to provide any hard and fast rules myself, just reporting trends from what I've noticed in successful samples.
In that case my sentiment is more appropriately expressed by "shown to be objectively sound or unsound." Not to imply that anyone does in fact do this in their samples, but it should at least be within the realm of possibility, which, again, as a general trend, isn't particularly endemic to many samples.
Thanks for your input! I appreciate it

I think this is partly right but perhaps not quite accurate. The key here is that you need to show an awareness of contemporary secondary literature on the topic. A paper on Hume or Aristotle can certainly be successful but to do so it's going to have to be responding to and/or taking into consideration the lines of debate that form current Hume or Aristotle scholarship. You mention Kripke, but a Kripke paper could be just as outdated if it doesn't take into account how others have responded to Kripke in recent years. It's less about the topic in this case and more about showing your awareness of the current conversations about the topic at hand (even if this occurs mostly in the footnotes).
I think the analytic-continental distinction is largely unhelpful and this is no different in the case of writing samples. What you need is clear, compelling prose that makes a coherent argument. This applies whether you're writing on Heidegger or David Lewis. If you're going to write on Heidegger, your prose better be closer to that of Dreyfus, Kelly, Carman, Wrathall, et al. than it is to Heidegger's. That being said, if you want to do German/French philosophy in a department that isn't primarily "continental", it would probably behoove you to demonstrate some awareness of major issues in analytic philosophy. Fit comes in here too. You have to think about who can support the sorts of projects you want to do and what sorts of students are typically admitted at the program in question. 
Yeah, maybe, but I expect this is a case where the exception proves the rule. Send your best work. If that happens to make a positive claim, then so be it. (I'm also skeptical how strong the distinction between a negative paper and a positive one really goes, but that's another story).

1. On most framework, arguments are valid/invalid, sound/unsound and propositions are true/false. Try to avoid that mistake in a writing sample.
2. You should certainly make sure your arguments are valid (especially if you present them in premise/conclusion form) and do everything you can to demonstrate the truth of your premises. I'm not quite sure what you mean by "can easily be shown to be objectively true or false" but if it's anything stronger than giving valid arguments and arguing for the soundness of the premises, then I'm not sure this occurs all that often in philosophy.
This is probably the single most important factor when it comes to graduate admissions (assuming everything else is in order). What it takes for you to get admitted is for someone on the admissions committee to get excited about your writing sample, hopefully multiple someones. This is also where fit comes in. Fit can occur in straightforward ways (applying with a writing sample on Aristotle is problematic if nobody in the department publishes on Aristotle) but also more complicated ways (if you reject a two-objects view of Kant in favor of a two-aspects view, then your odds of getting accepted at Brown to work with Guyer on the first critique are probably pretty low).