I think you biggest problem is going to be buying the aircraft! I am pretty sure it is not possible for a non-resident foreigner to own directly an N-reg aircraft.
I seriously doubt a low time PPL 'knows how to fly instruments' - unless you have forgotten to tell us that he has high time on his Air Force ticket and has just recently applied for his PPL.
However, if he does actually know how to fly instruments, that would imply he has some logged time and some instruction. If he is just knocking off the rating 15 hours instruction in a 172 and the test and its job done for maybe $2000. You may even be able to get by with only 3 hours (depending on the qualifications of the person who did the original instructing).
If your instructor is a high time Meridian pilot and an instructor, then there should be only a limited issue getting insurance. Sometimes people find it a hassle to get US insurance if they are not resident (and you typically will have to buy a years cover and then cancel it after 6 months). It may also be a bit of a challenge to get insurance to instruct for two non-resident pilots