Charles,
Duncan's already answered one of your questions. I also believe that some single frames were removed just before major violence, e.g. you don't always see axes, spears, et al making their full impact into people's faces, etc.
As for the 2nd DVD, on R2, it has a 27 minute documentary and a couple of trailers. The R1 version, has all of this, but all on one disc.
Ultimately, if you go for R1, it will be uncut, and have all of the extras on one disc, and you'll be able to get it for about £15-£16. With R2, you're getting a censored version, with a second disc of stuff, that should've fitted onto one disc, and at about £17-£18. Also, bear in mind that by buying the R2 version, you are (to some degree) telling Fox that it's okay to release p*ss-poor double-disc DVD's with bugger-all extras on them! No, no, no!
However, which you choose, is entirely up to you.
Pooch