what desert colour best suits an armoured vehicle in iraq? XF-60 Desert yellow.....or XF-57 Buff?

Your going to have to mix the two colors if that is all you have. One is to dark and too yellow and the other is to light.

I agree a mix of both will bring out the best shade.

do you think that its a good idea to paint the interior of a humvee if i'm going to close it up anyway?

If the windows will be transparent I’ld paint it.
If you can’t see in theres no reason to.

the windows are transparent, but when I put the roof on, its too dark to actually see in. the only part that you can really see is the radio and the seats.i'll upload some pictures of i soon

Even if you're not opening the doors or the rear hatch, I would still paint the interior in its basic overall color. I would not, however, bother doing a lot of detail painting or decaling inside, since it won't be visible. Just the overall medium green or sand with the seats and steering wheel painted the right colors, and that should do the trick. If you want to do a bit more than just basic painting, focus on weathering the interior rather than detailing it. That's the approach I took with my M1025, and I like the results.