Bud Valley:
Regarding #1, I don't think it has anything to with access concentration, early stages of practice, etc. I've been sitting daily for about a year now and think (hope!) I am beyond that point by now. I also suspect I may already have hit A&P, which I described in another post (here: http://www.dharmaoverground.org/web/guest/discussion/-/message_boards/message/2297782)
Thanks for the link. That certainly sounds a lot like an A&P event, and probably was.
However, that doesn't mean you're not getting stuck in the lower stages (1-3) during recent sits.
For example, I crossed the A&P quite powerfully in the Summer of 2008. From then up until stream entry in February of 2009, I cycled through all of the lower stages I had access to in almost every sit. Sometimes I would randomly get stuck in the 3rd or 10th stage during the day, which was always really uncomfortable (those the the two most likely places to get stuck).
If you're not cycling through the A&P during sits, and you're getting all of these weird tensions and contortions in your body, you may be getting stuck in the 3rd stage all over again. It could be something else as well, but the description you gave sounds the most like stage 3. Stage 10 is also a possibility, but it doesn't make as much sense in light of the fact that you don't pass through the A&P when you sit (unless I'm missing something).
I guess it's natural to think that we can save our place in the cycle, like it's a video game or something. But it doesn't work that way. We just go with what we're given.
Noting the Four Foundations is an excellent practice, so keep it up. Not everyone likes working with the breath in the way I suggested, so stick with what works for you and forget that I brought it up ;-)
I still think mild exercise and stretching could help, if you don't already do those things. Otherwise, get into your best posture and just keep on noting. These things have a way of working themselves over time, if we let them.
Best!
-Jackson