I noticed Baratheon and Martel have special house cards, is there special house cards for the other Houses?

What does the infinite sign in front of the title of a card mean?

Baratheon, Martell, and Greyjoy each have custom house cards that have been manufactured for the LCG. I assume FFG plans to release the other 3 eventually, but none have been announced yet.

The Infinity symbol means some sort of recursion, in which you can return the card to play or to your hand based on certain circumstances. Effectively being able to play the cards "infinite" times.