The edit tab has always gone away within about 5 minutes here. But if you click on it before the time is up and start editing, then you may be too late to post...
I don't use the mark forums read feature, so I have no idea on that one (but see admin fixed it). The 5 minute rule and the first few posts subject to moderator queue feature are really nice things that YT has in place. I think we've all had times whhere we've wanted to go back and edit posts hours later, but by that time a thread can be 20+ posts longer. It would change the meaning of things too much. Also, I don't like spam and I appreciate the moderation setting. A handful of my posts as a newbie were checked as well. While it was kinda irritating and confusing at the time, it's well worth it.