Thanks for the all the feedback. There are already notifications, and they get emailed to you if you don't log on to the site for a while. If you aren't seeing them it's a bug!
I think flair on posts is fun and can be useful. I'm thinking maybe it can be some kind of opt in system. (reddit is kinda similar where some subreddits let you add an icon.) Whether postcounts should be shown on the post, I could go either way on it. It's definitely useful to gauge someone's seniority from their post, but I think it's more common now to use a registration date. (When we have community profiles there will be things like postcounts there, so it won't be completely lost)