Spam email...I guess? I mean, I don't know what else they can do with my name and address, really. Identity theft, maybe? The credit card information is the worse of it. Thankfully, I've never wanted to use a credit card on PSN. I always opt to get PSN cards. 
Could Identity theft happen with just your name and address, though? Or does the credit card information pretty much seal the deal?
Playstation Plus members SHOULD have they're memberships extended for however long this things lasts. If it lasts another two weeks, then all that time should be extended. That's a given. 
Sony is looking worse the longer this lasts. I can't feel sorry for them, but I do for us PS3 owners. It's just hard for me to feel bad for them in a scenario where they're supposed to be able to prevent this.