I have no forum subscriptions, and no notification on reply, yet as many of you may have noticed I manage to keep up with a large fraction of what goes on at this board.
1. I'd be happy to donate. PayPal sounds best, but I'll even send cash if that is the only thing you can handle without getting buried in administrivia.
2. If spam black-listing is the only problem then emails only on paid membership sounds like a good solution. Or you could turn emails off altogether so far as I am concerned.
3. Pass-thru revenue doesn't sound like something I would make much use of, since I make very few internet purchases, but it wouldn't bother me if you had it.
4. If you had a paid membership, I would be pay for it.
5. I'd be disappointed to see you go to advertising, though if you suppressed it for paid members, and if it didn't slow response for those members, I guess I wouldn't complain. (i.e. I would hope for PHP or other server-side ad suppression, but not client-side script, and certainly not client-side Java.)
End of April 2013: Traded my 2011 SL for a 2013 S with charge pkg.