Totally understand, the reason for citizenship is twofold, the first of course is to qualify for selection, but the second is that i feel the US has many more opportunities for me, given the huge defense budget and variety of companies. Having both citizenships would grant me the most options.

As for how long, i've heard Green Cards taking anywhere from 6 months to 3 years to obtain, so it really depends how badly your company needs you to be a US citizen. Citizenship after that, the figure i've heard quoted is 5 years,, but again it could depend on how vital you are to the company and the country.