First, the two issues that I can give you some information about:
-The server has been sluggish, and I've hired someone to fix that. I'm fairly certain that the slowdown is a remnant of the downtime and related complications, but I'll leave the final analysis to the professional. I'll post updates as I learn more, and I don't expect it to take more than a few days to solve.
-The email client is disabled, which is why you aren't getting emails. This was a quick-fix to get server speeds up, and once everything else is squared away, that too will be fixed.
Now the new issue:
I don't know why posts would be disappearing, other than the server timing-out while a post is being made. If a post completes (i.e. you get to the board-generated post complete screen), it should be there for good. If posts disappear in spite of all indications that posting was successful, let me know immediately, because that's something else I'll have to look into. It might be another aspect of the slow server speeds, but again I'd leave it to the professional to make that call.
Let me know if you encounter any other problems, and thanks for sticking it out.
User Control Panel > Board preference > Edit display options > Display signatures: No.