I'd recommend taking a look at one book from each discipline so that you have a good idea as to what the course is going to entail.
Personally I'd go for;
Archaeology: The Human Past - Chris Scarre,
Social Anthroplogy: Small Places, Large Issues - Eriksen
Biological Anthropology: How Humans Evolved - Boyd & Silk
Each would give you a fairly entry level overview of each subject. The other thing to familiarise yourself with is the Part I handbook which is put up online on the Arch & Anth website. It gives more information as to what is covered in each paper, and preliminary reading lists (though you are not expected to cover these yet).
It makes no real difference. Your college will be the place in which you are living, eating, socialising etc, and so college choice should reflect those things.
For example, if there is a particular sport that you are interested in, pick a college that offers it.
I'd really advise coming to Cambridge to visit the colleges if at all possible.
The undergraduate Part I handbook contains a list (right at the back) of the Director of Studies for Arch & Anth at each college if you are at all interested, though having a DoS who is not from "your" discipline will not adversely affect your degree in any way.
Anything that helps demonstrate an interest in, or passion for, the subject would not be a bad thing to have in your Personal Statement.
The Cambridge Prospective Undergraduate Arch & Anth page has a list that will give you some further information as to what to expect as it differs a little by college.
Some colleges will want you to send work in for them to see prior to interview, others give a test on the day of the interview etc. The "type" of interviews may also vary. I had a "subject" interview that was very academically based, and then a "general" interview that did not discuss my subject at all. Fellow students at different colleges have said that they had two interviews, though there was no such distinction.
Once you have settled on a college choice, check the Undergraduate page, and the subject page on the specific college website.
As a general point, the A&A interview is really no different to any other subject interview. The information held on TSR about Cambridge interviews is very useful, and will be worth reading.
Best of luck