#1
My left hand (righty) was injured in the military and I broke all my metacarpals other than my pinky's. I have good enough grip but kind of an awkward hold to the guitar neck.

Anyway, long story short, I find it easier to use my ring finger (rather the side of it) most of the time as opposed to using my pinky to press on the strings. I think it's compensation due to the fact my pinky is kind of on a different rotation angle than the rest of my fingers (slight).

Question is, should I continue to use my ringfinger in every scenario where I can (three string chords will usually be index and ring) or should I try to include my pinky in simple chords just to add dexterity to it and help in the long run?

I understand everyone plays differently, and it's entirely possible to adapt to a unique style of playing due to that hindrance, but I'm interested in what other viewpoints are.
#2
Whatever works the best. Nobody really plays the same. If you want to improve the dexterity of your pinky, you could use a gripmaster, but they can get expensive ($9.95 - $24.95) if you can use your pinky, go ahead. I'm not here to tell you know, so do whatever fits both the song(s)/chord(s) and the comfort ability. Sometimes, playing weird can develop bad habits, but you can't do anything about an injured pinky other than to let it heal.