I never really have an issue with humidity....I always wonder why people talk about that being a problem.....other than sweating my self to death....

and yes slow slow slow catalyst. As for acrylic anything....I cant answer. I painted a trailer with single stage once and vowed never to paint with it again....not my area of expertise. Some of the other guys on here that are a little older than I could answer your questions regarding that. good luck with the paint job.

Josh