I am getting the core set for Xmas. Seeing as I won't have a second core set right away...is it ok to reuse cards. For example, if the Stark player loses Eddard Stark I'd like to be able to return that card to the deck and replay it. I was thinking reusing certain cards could get me by until I get extra cards. Thanks for any help.

There is nothing in the rules that allows you to return cards from your dead or discard pile to your deck just because you'd like to play them again.

That said, there is nothing wrong with making up your own house rules to keep the game fun for you. Another option would be to use proxies.

If you're looking for singles, I sell and trade: http://www.tradecardsonline.com/user/kauai