We expect to have full web interface soon. Good topics, good people, generally good discussions. Others may just have hit at the wrong season when people were starting a new term, getting ready for finals, on vacation, etc. I personally wonder whether moderation in the sense that has been done in the past is really necessary. Personally, I find a more interactive mode preferable, but I do understand the other view.
None come to mind as far as utility, but just about every one was interesting and informative.
Only as cited below in 5. I'll be really heretical and suggest that you consider a new name for the list. The current name isn't intuitively obvious to anyone, and I'll bet that half or more of the members now couldn't tell you what the name means. If you want to recruit by other means than word of mouth, you'll do much better with a more descriptive name. Post info about the list on other relevant lists.