I have a big gun safe. I will start putting them in there, and will put a couple gel packs in also. I know the safe has plenty of room, as I only have a few long guns and a few hand guns in there. I know there is a couple of Colts from WW1. The rest are just my hunting equipment from my younger days.
Bad idea. The oils and cleaning solvents from the guns are bad for the coins. Whatever container you use, it needs to be used for coins only.
You'd be surprised. I bought a really nice safe off of Craigslist about a year and a half ago for $100.
You don't "need" a safe. Like I said, a Tupperware or Rubbermaid container works just as well. They sell 'em at Walmart for what - $15 ?
Looked on CL in the Raleigh area, which is where I'm gonna guess you are... http://raleigh.craigslist.org/for/1782619134.html 65 bucks.