Hello fellow AF guy. Good luck with your purchase. Be ready for some pretty funny looks from the people on base. Since I just baught my car last week, I thought I might give you a couple pointers from my search.
First, your loan. I don't know your credit history or anything like that, but if its not too late, check out Penfed. They are actually an affiliate of USAA and I was able to get my loan on a 03 for 2.5%. They work just like USAA where they send a check that you and the buyer has to sign.
Second, insurance. I am down in florida and am pretty shocked how the different major insurance companies will fluctuate with their rates. When you get the viper insured, really shop around. It has been discussed a lot on this forum, but a little time behind a computer getting quotes can save a lot of money. For instance, before I got the viper, we have a 2010 honda ridgeline and a 2006 subaru legacy with full coverage. USAA wanted $1200/6 months. Alstate wanted $885/6 months, and Geico wanted $600/6 months. We switched to Geico from alstate and so far so good. Now with the viper added, its $960/6 months. I know a lot of military guys only will use USAA, and thats great if the rates are good, but its a good idea to always shop around.