If he's taking the bottle now, introducing it once a day won't hurt. Perhaps at a time when you need some "me" time and can get your DH to do it. I also think that once a day is fine because when you're not there he will have no choice but to take the bottle, kwim? And if there isn't a problem now, there should be no problem later?
IMO, your supply shouldn't be affected either, especially since you plan to pump while away from him.
Are you pumping currently? It's up to you whether you want to dip into your stash. I would recommend just pumping for those daily feedings and keeping the stash intact.:gvibes
I would say keep your stash intact unless you have older bags of milk, then you probably want to rotate them out. I rotate about 2 bags a week since I have bags that are 2.5 months old that I dont want to "go bad" before I need them. If you dont need to rotate, I wouldnt b/c 1) your milk looses some of the "good stuff" when it is frozen, so the more fresh milk your lo gets the better 2) storage bags are expensive!! rotating your stash can get pricy fast.