Good luck on your build, Chris.
I have lots of reference photos, but unfortunately, due to the scourge that is dial-up internet, I could spend all week uploading them. So if there is anything specific I can help you out with, let me know and maybe I can send an email. In the meantime, here are some great reference photos on the web:
http://212.158.133.3/hwa/randy_smith/AH-1W/index.htm
http://212.158.133.3/hwa/randy_smith/AH-1W(COCKPIT)/index.htm
Also, check out the airliners.net photo search engine. At least a dozen high-res exterior shots there.
The Cobra Company resin update set is outstanding, but necessary only if you want a totally up-to-date NTS Cobra. The MRC (AFV) kit in itself is a fine representation, so it's just going to be a personal decision on if you want to super-detail it or not.
Twobobs decals are the way to go. There are a few specialty schemes on the "Whiskeys in the Mix" sheet (some really cool snakes that go down the side of the fuselage, and some nose-art), but plenty on there to provide a basic scheme, too. All the stencils and aircraft 'strip-lights' are included on the sheet as well.
Keep us posted.