You have a good chance. I wouldn't advise re-taking the GRE. Your scores are fine, especially since you got 4.5 on the AW. Your research experience will help immensley although the adcom may wonder why you haven't published in your three years of research. Assuming your LoRs are good, you'll be ok.
I assume you're applying for the thesis option?
Good luck!
Is your four years of research experience full-time?
I think you should be ok if you can give a reasonable explanation for the low GPA in your SoP. You've done quite a bit to make up for it.
Sorry to hear...
Are you sure you submitted your GRE scores and any other supporting documents that were required? This could be the reason for the swift decision.
ComtriS, I'm in a similar boat. I've been in industry for 2 years on my BS and i'm looking to obtain a MS. Out of curiousity, who did you get to write your LORs?
Congrats on your acceptances!
Honestly, it is probably a little difficult to answer your question because course requirements not only vary university by university but also from course to course.
In general however, each course usually will have 2-3 assignments. These assignments can be thought of as mini-projects more homework sets.