A few questions about how the show works.
What are the allowable luxury items each contestant can choose?
How much do the contestants who get voted off get paid?
Are members from rival tribes prohibited from meeting before the merger?
**
I don’t know the exact amount, but from Survivor Site Rules Page:
Also on the page it mentions that the players are not allowed to share the $1,000,000 or conspire to share it; there can only be one. 
Well, they meet at the challenges. I don’t think they can talk in great detail, but somethings might be said (I haven’t watched the show that much, so am not sure).
I don’t think there is a list, per se. But there are certain things they obviously won’t allow. For example, Debb tried to get a lighter as her luxury item. Yeah, right.
As Rob indicated, it varies according to how long you stick around.
Other than briefly at the challenges, yes. In fact, I read that at one early challenge (I think it was the cliff jumping), the production crew was trying to get things set up and the tribes started talking to each other. Producers quickly ran in and separated the groups.
It looks like your questions are answered. Just as a brief note, I would like to mention that in the flood of interviews following the conclusion of the first Survivor, several of them mentioned that they were not allowed to speak to the other tribe before the merger.
The newspaper also ran an article about the luxery items. They must be for luxery. Anything that would give one team an edge over the other is prohibited. The frying pan that Keith brought (it was some kind of specialized cooking pan, but I’m not a cook) was ok, but a lighter was not.
What about sneaky luxury items? On the first series, one contestant brought eyeglasses, which were used to start a fire. On the current series, one contestant brought a flag, which he admitted he had brought with the intention of using as a shelter roof.
My luxury item? I’d bring a crate full of Ensure.
Well, if they’re sneaky and creative enough, they’re probably okay. I mean, a flag may help a little, but it isn’t exactly a great roof to have over your head. I don’t think it gives any real advantage. The glasses did, but they had to be creative enough to think of it, first. And the folks at Survivor would be hard-pressed to tell a guy that he can’t wear his own glasses!
(But you’d better believe that if I ever got on the show, I’d get a prescription that would allow me to start fires that way, too – and I’d practice!)
Id bring some prescription glasses (not too strong) that can start a flame & which are also used for swimming. That way I could see the fish underwater! Viola! food.