Thank you very much for 2) - this will allow me to considerably lessen the amount of infrastructure I'm having to take care of (pgbouncer can go now).
About 3: That's what I was using before moving to tsearch, but pg_trgm based suggestions sometimes were really senseless and confusing to users. Also, using pg_trgm for suggestion will cause suggestions to be shown that then don't return results when I later run the real search using tsearch.
I'm happy with my current hack though, so I just wanted to give a heads-up.
2) There is a shared dict extension that load the dict only once. See: http://pgxn.org/dist/shared_ispell/
3) About the suggestions: you should look at pg_trgm contrib extension.