Looking to get started on group content - a few questions

I haven't played much TESO at all, and I'm getting back on it now.

One thing I'm curious about is the group content, I haven't tried any of that yet, so I have a few questions.

I'm currently level 18, for what that might be relevant.

1. How does level the level sync works with parties outside of instances? And inside of instances?

2. There's a "Dungeon Finder" in the game, right? I remember reading that it wasn't very useful, is that still the case? How do people generally go about finding PUGs?

3. As a low level player, what are the limits I should be aware when PUGing? If I join a high level party, will enemies be synced to their level? Or to my level? Will the party be synced down?

4. Do dungeons have minimum level? And maximum sync level?

5. When I do find a group, how do we join the dungeon? I suppose it's automatic via the Dungeon Finder; for other means do we need to manually walk to the dungeon entrance?

6. How do roles and party composition work?

Thanks!