I also keep my tubes stored in baggies with a little talcum powder. (Whether in my tool box or bike bag.). The talcum helps the tube "behave" better as it doesn't want to stick to the tire and moves freely. Also the talcum/baggie keeps the tube from rubbing against the bike bag. Friction can compromise the tube before you use it.

I use my valve caps until I lose them, usually about the fifth time I air up the tire. :-)