The hazardous fire pay and tax free are nice and add up if you don't spend it, but living on just what the army issues you and eating at the chow hall are possible, but not wanted. I did two tours in Iraq and 1 in Afghanistan and each time I went over with my ta-50 and a few personnel items(plus extra uniforms etc..) and when I got back I had shipped 2 foot lockers through apo and then had a couple of duffels bags extra as well. Basicly the only bastion of sanity if being able to relax after the end of the day/night and read a book, watch a dvd, play a video game, etc.. and have some snacks (all bought at the px/bx) . You can get tired of mess hall food real quick and I personally never ate any of the food that the Hajii's were selling on the side of the road, but my buddies did and they were always compalining of stomach problems. The only time I ever spent big buck was when we went to the brits FOB and they had real beer and even whiskey, also good for trading them our MRE's for real food.
Basicly when you are deployed you somehow seem to spend a lot of the "extra" money and what's left over my wife spent. Also those of us with families have a hard time making ends meet, heck, before I got out I was a Staff Sergeant with 6 years in with 2 kids and a wife and I qualified for food stamps (didn't take them because of pride thing), pretty sorry , Now I make 5 times as much when in the military. So that "extra" money is spent before we even get it, if I hadn't been deployed 4 out of 6 years I don't know how we would have made ends meet without the extra pay.
As far as bring backs, I know of guys that tried and got caught and I know of guys that didn't get caught. I never did it, but I did find a couple of grenades and loose ammo in my LBE when I got back and I promptly turned it into the provost marshall and they only asked me why I hadn't turned it it sooner and made me fill out some forms and that was it.
If you do have an old "bring back" from NAM I would keep it hidden and don't brag about it and don't be stupid and shoot it at the range. Otherwise don't try to bring one back now for all you guys that are over there now, unless you like to spend a lot of time behind bars.