Alceister pretty much hit the nail on the head. Importing replica firearms is definitely a no-no, but buying in-country is pretty simple in terms of legality - just be over 18 years of age. Expect to pay more than you would if you were living in the States, however: a 200-300% markup is the norm around here.
Importing gear is usually kosher, as are your gun's internals. There are some pieces of gear you cannot import, chief among those (at least for me) are magazines with fake bullets in them.
One of the first things you should do when you're all settled in is to go to a game with an Age Verifier in attendance and get them to age verify you. (bring along a piece of photo ID!) From there you will have access to the AV discussion section, the AV retailers, and the "juicy" section of the classifieds.