1. For lower level dungeons, there's the low roulette that people often sign up for, don't expect a very social experience from those people though.. They generally want quick and clean runs for their tomes. Best bet would be to find a nice FC/LS, or make sure you level with your friends as much as you can.

2. Level 50 content is still level 50, didn't get scaled up. However, you can run them as level 50 synced group rather than go in as a level 60 group, or go in with an undersized group and try to duo the primals

3. They're okay, there's a LOT of Au Ra running around though =)