zoo7

I agree with RepatMan on discussing SOP structure with POIs in your communication with them. I also think it would be appropriate to request a conversation via Skype if you have already established contact with potential advisors. During the application process for my current program, I had established contact with my now advisor and several other faculty members, and they offered to review my SOP before I submitted, as well as a Skype call to answer my questions. I don't necessarily think that's the norm, but if a POI offers, take the opportunity, and if not, I think it's very appropriate and useful to ask for general SOP advice.
Students who are asked to interview for funding purposes and program fit are also typical contacted for Skype conversations, based on my and my peers' experiences. Establishing strong points of contact with potential faculty advisors is critical in the application process for Anthropology, in my opinion. Good luck!

It's generally considered unethical for PIs to review application materials. I wouldn't ask, but you could probably ask if they would allow you to discuss how you hope to lay it out or what you will discuss within it.
Chatting with folks over skype or whatever is pretty crucial. Odds are that there will be a great deal of qualified applicants and normally faculty go to bat for those that they have confidence they'll like working with. So it would be ok to ask a PI or other faculty to chat to discuss your fit in the program, both academically and personally.

So just to update you guys, instead of bugging the faculty members again, I sought out the program coordinators/grad advisors to ask if they knew if the faculty members I was interested in working with were accepting grad students. I immediately got replies from POIs from one school, and the coordinator from another advised me on who were the faculty members who were accepting students and who weren't which was the more important question I needed answering (apart from feedback if they thought I was a good fit for their lab/program). Thanks for the input guys!

Have you checked out the work of S Low at CUNY? She and a number of others work on urban space, and there are a lot of people (including D-A Davis) who work on gender. 

Your writing sample should be your most polished piece of work, preferably something presented at a conference and/or peer-reviewed or published, even if it is in conference proceedings. Barring that, I would go with your strongest paper (perhaps a senior thesis if undergrad, MA thesis or capstone, etc) that connects the most with your program(s) of choice and/or highlights your specialization and skills. So if you are writing for a program with faculty who specialize in gender, select something in that area. If you are writing about popular culture and nationalism, you could potentially frame that in your SOP for departments focused on media, youth culture, nationalism, popular culture, etc. Your sample is just that, a sample. IMO I would probably take your strongest work and submit it as last graded or as published. If you have revisions from a trusted advisor's input, then go for that. However, I think your writing sample is less important then showing in your SOP how your previous work connects to the department and your current plans. Search committees and admit committees will probably not read and entire sample, so it can be risky trying to tweak a 20, 30, 40, etc page paper at the cost of your letters of rec and SOP. IMO your SOP is your campaign platform and sales pitch. It is written for that program, or should mostly be original and written specifically for them.