#15 (just because I can!) -- What happened with the number sign? You mean #?
#12 -- PMs: The counter on the front page shows 'unread' PMs, and in the migration to TT4 all PMs stored in your inbox AND outbox were reset to "unread". To remedy this, go to your inbox, click the box in the blue bar to toggle all the messages, click Mark As --> Read. If you have multiple pages of PMs you'll have to go through the pages and repeat this action.
This will still leave messages in your outbox unread. What really is a bug, I think, is that outbox messages are marked 'unread' -- How can sent messages be unread? -- and there's no "toggle all" button in the outbox, so you'll have to click on one, and then with next - next - next go through them all. Once you open them they are marked as read. Once your counter is down to zero, PM on the front page will not be bold anymore, and you'll notice when you have a new PM.