The first three are right. As for 4, it's not so much that I prefer less communication as that I sometimes may be too busy to visit the site.
I think the thing people may not understand is that I can only work on Arc intermittently. In the spring as well as a YC cycle we had startup school and I got married. The next day the summer YC cycle started. During the summer I was busy with a larger than usual number of startups. As soon as it was over I went on honeymoon, during which I barely touched a computer. I got back to the US just before applications for the winter cycle were due. I've been reading them all the past week, and I still have over 100 left. (I probably wouldn't even be writing this if I weren't desperate for ways to procrastinate.) Then we have to move YC and ourselves to the west coast, then do interviews. I'm hoping that I'll be free to work on Arc in mid or late November, but I don't want to promise anything.
So it's not so much that I don't want to be held to a schedule as that I couldn't do things to a schedule even if I wanted to.
I'm hoping that ultimately doing so many things will make them all turn out better. But it does mean I can't do any of them more than part time.
In answer to your specific questions: I don't think I can commit to an upper bound for new releases, because the factors that determine whether or not I can work on Arc aren't cyclic. Yes, I'll incorporate bug fixes, the next time I get to work on the language, which I hope will be late this year. At the moment the most valuable things people interested in Arc could do are (a) find bugs in the current implementation, (b) think about the core language and specifically what new operators, if they existed, would make existing Arc programs like news.arc significantly smaller in tokens, and (c) try using Arc to write different kinds of applications and report what happens.