There isn't anything wrong with the link as far as I can tell.
This link is as non-fishy as you can get: www.amazon.com/dp/B00GAC1BN2/. The only thing we could take out would be the ASIN, but then it would just error out/go to the home page.
I don't know why it is asking you to re-enter your info, but it made me do that when I purchased dark souls. As long indentity information matches the domain name, I'd say you're good.
this is what i get http://www.amazon.com/dp/B00GAC1BN2/ref=cm_sw_su_dp
No, it is not. It is amazon's short url. It is the same thing as http://amazon.com/dp/B00GAC1BN2 but much easier to type out (they both include the ASIN code.