First, welcome...
You are about to play a d**n good game : )
Just know the 1ed has been living for a while already:
There was 6 extentions:
TV
Movie
Watcher's chronicles
Movie 2 The gathering
Arm & Tactics
Four Horsemen
That is 31 immortals to play with
You will be able to find boxes for some of those extentions.
For others, it will be very hard.
The advantage is if you find cards, there will be usually very cheap. But some you will have a very hard time to find..
The 2ed is not yet 1 year old.
The 2 first beta expansions have only been available online.
The game should be available in game stores from the next expansion: Ramirez.
The 2ed is not as rich and complex as the first one yet (because it is quite new), but all the cards should be easier to get.
At last, you have to know that 50% at least of the 2ed cards can be played with the 1ed.
Do not hesitate to ask any other questions.