Pull the gauge straight out(you might have to turn it left and right a little), the plug should turn a little to the left and come right out. I'm not sure what bulb they are, but once you get it out, any autoparts store should have it.
I had 15% all the way around(except windshield of course) and I got a tint warning. I replaced the front with 35% and haven't had problems since. The 15% up front was a pain in the ass to see out at night IMO.