Okay, so how you unlock more Avatars and Titles is quite simple. For Endless Legend and Endless Space 2, it's all about owning more DLC expansion packs. For others, it requires a bit more work. Let's say you want to unlock x avatar from Endless Space 1 and y title from Dungeon of the Endless. 

Instead of just hovering over the title like you've said, click on it.

After clicking on it, it should bring you to this page

Alright, so each of those achievements is an unlockable achievement from Steam (to find them just open Steam, and it should say achievements lol)

For the ES1 ones, most of them can be unlocked in a simple one or two games, read the description of the achievement on Steam, it'll tell you exactly how to do it (i.e explore 100% of the galaxy in x turns), load up the game, complete the achievement, log out, connect your Steam account to G2G again, and VOILA ! You've successfully unlocked the achievement.  

Completing the achievements will automatically complete the shapeshifter and collector achievements for you. The others are really about adding to the games, and their simple descriptions like, "received 10 votes on a thread" aren't easy, but it's as simple as writing a good thread and hoping people upvote it. 

If you have any more questions or need more clarification (as I was kinda vague in this) just ask lol

Hopefully, this helps !