I'd use whatever oil weight the owner's manual for your car recommends and nothing else unless you really have a good reason to. It probably recommends two different weights and different temperature ranges that each are suitable for.

Amsoil is definitely the way to go, or Redline if you feel like spending a couple dollars more per quart. If you have a local dealer for either, get that one :) It's annoying to have to keep a large stock of oil just so that I can change it when needed.

Awesome purchase and welcome to the forum.