I brought him along to the Military Base thinking he'd have some kind of cool special dialogue being the nerd I am. This is the first time I've brought him along for heavy combat outside of things like random encounters. All he does is switch around between weapons I've given him, pick up random looted weapons he WANTS to use, and EXTREMELY OCCASIONALLY (I mean once in a blue moon here) he completely blows a super mutant away with his minigun. Is this a common issue with him or am I missing something?

You have to fiddle with his combat movement commands. IIRC his default is something like "charge" so he wont shoot until he's point blank. Tell him to "stay where you are" or what ever and he'll just stand and shoot stuff.

Like Andaius said; play around with his combat settings. Also, if you're using him as a pack mule, either give him empty weapons or just ammo. But never ammo and a weapon he can use other then the one you want him to use.

The bozar is a really nice choice if you don't mind him shooting you and your other companions in the back (save often). If you want him to fire a single shot weapon, the (turbo)plasmarifle is a good choice.

Indeed, I give him either a laser or plasma if you want him to stand and shoot. If you give him automatics be sure to give him a clear path or let him charge to point blank. You might have to be some what weary of attacking stronger enemies too since he doesn't use armor. at higher levels his natural toughness will equal combat armor, but he'll take a while to get there.