I believe they only use USPS and UPS.
They're usually a couple of weeks behind the Japan release since it takes a little bit for them to get it in. But for the price with cheaper shipping, I don't mind the extra wait.
I used a code they sent me from my last purchase, but usually if you make an account on their site they'll email you a 10% off code. Or if you leave a item in your cart for long while signed in, they'll email you a code.
Pretty sure it's a kit since it's part of Bandai's Perfect Grade line, and every Perfect Grade I've built and know of is a model kit.
I'm definitely getting this. Already got it pre-ordered for $342. :)