1) We're willing to be flexible on this, as needed. You can roll for the chance to find one randomly on Red Team territory, or you can assume that one of the War Units was nice enough to lend you one that they might have had on hand. Most of them will be rather on the rudimentary side - think early blunderbuss-styled firearms, which means that they have very simple mechanisms and might break easily. The plus side is that they don't require ammunition - anything from a fistful of sharpnel to pebbles will do, as long as you have a way of lighting up the projectiles with gunpowder or fire.

2) They're perfectly able to use their iStones, if you like. The question is more of whether or not they would, or whether they'd remember how to use one. The memories leaking into the minds of other characters entail no recollection of what these tools are, and how they might work. Or whether they can trust them.