Ty,
I have the creative cloud service it is “not to good to be true”. Yes since you have a CS5.5 License that will qualify you for the special $30 pricing. Keep in mind this is just for a year, then it goes to the normal rate. It lets you run it on 2 computers at the same time.
As far as 6.5 or 7 – I’m assuming part of the membership means you would get all updates as they comes out. This was a genius step for adobe, I think it should end a lot of piracy as well.