Hi bluebicycle. I've been to DBSA meetings many times in the past. I have never been to a NAMI support group, but have attended a WRAP there. In answer to your 4 questions:

1. Initially I didn't have anxiety. In fact, I was often hypomanic or near manic when I attended, but the facilitators were understanding. They would reel me in at times. But there did come a time when it was next to impossible to get me out of the house. I experienced some agoraphobia. The time came again when I wanted to attend. I was still nervous to leave home, but I'd get there and the meeting wasn't as bad as I thought. Or sometimes I went and only stayed for part of the meeting. They were OK with that. I didn't feel funny leaving early when I needed to.

2. I could understand people being triggered by very depressive talk, like hopelessness or expressions of suicidal ideations. Actually, I did not hear much of the latter. I think that if such talk could trigger you that you should ask for those speakers to talk last, or announce it as a trigger warning so you could step out briefly to get a drink. I actually had more triggers from manic members, especially if I was on the cusp of mania. In these cases it is again good to step out, or hopefully if the facilitators are really good and perceptive they can step in. Really, I don't remember being triggered that often, but that's me. Others may be more easily triggered.

3. You are not expected to share, if you don't want to. They generally do want you to give your name, which could be made up. Or even if you don't want to give a name you can just say "I'm here for the meeting, but would rather not share." If a facilitator pushes for more, then I'd complain to the head facilitator by e-mail.

4. Most people at the DBSA meetings share their dxs. I don't know about at NAMI support group meetings, since I've never attended one. Again, I don't think you need to share your dx, if you don't want to. You could say the same thing (or similar) that I quoted above.