You need to sign up for a creator's club account to be able to submit to Xbox Live Indie Games. It's $99/year, but it's what allows you to develop and release on the Xbox.
People are still releasing XBLIGs, so it's definitely not disabled
To expand on Jutaris' comments, XNA is not DEAD. It's just not being developed anymore.
However, everything that XNA has done in the past (PC/Xbox/Windows Phone 7 games), you can STILL DO. You can still get XNA, you can still write games with it, you can still release those games on any of the ever-supported platforms.
All "XNA is dead" really means, as it's stated is that Microsoft is no longer planning new revisions of it, so we're stuck with XNA 4.0 unless they change their minds.
It said quite plainly in the "rate this user" dialogue what it meant. I am sorry that so many people don't read the dialogue before clicking it or assume that it means something that it isn't meant to.
You're right. It very clearly said something along the lines of "helpful or friendly" which is not, at all, just the "technical competence" that you have mentioned.
Overall, I basically agree with MikeP. While I do like the concept of rating posts rather than users, I feel like not being able to rate posts DOWN is, overall, a detriment to the community in my opinion.