Yes, you can use a dimmer with these lights and it doesn't matter which one as long as it is 120v. I hope this helps.
Source: Illume Representative

Home Depot sells the bulbs, but they're not with the rest of the bulbs. For some reason they have a separate section far away from the rest of the lighting with some more undercabinet lights, and that's where they keep the Xenon bulbs. A very strange arrangement, I think.
Once you have the new bulb, just remove the puck's lens by unscrewing it slightly and pulling it off. Then pull the old bulb straight out (don't twist it). Carefully line the new bulb up with the socket and push it straight in. Make sure it's lined up very straight both horizontally and vertically before you push. It's a bit tricky because there is barely enough room to get the bulb lined up straight, and once you do there is no room to get your finger on the end of the bulb. So you have to grip it very hard by the sides. Don't wiggle it in because the glass is a bit too easy to break (as I learned on the first one I plugged in). When it's seated in firmly, screw the lens back on. You might need to turn it backwards (as if to loosen it) a bit until the tabs line up and it pops into place, and then tighen it. If the fixture pulls out of the case a bit in this process just push it firmly back in.