It depends on what you want. For AM parts I direct you to www.starshipmodeler.com and www.mechaskunk.com
For paint that is your option. Depends on what is avaliable where you are. I use model masters enamel paints personally.
Best way to build, is the same way as always for a gundam kit. read instructions a few times, open all the peg holes slightly so it can be taken appart. Fit it together make sure you know what goes where. Build dependant parts, like joints and such, then build the rest, fix the seams, prime, paint, clear coat, decal, clear coat.