A few years ago, for swim team, I decided to shave my thighs and legs (I'm a guy, so this isn't really the norm). I've since quit swim team, but there's a radical difference between the hair growth on my calves and the hair growth on my outer thighs. The hair on my calves has grown back normally, but the hair on my outer thighs is broken, rough, uneven, and the skin suffers from growths similar to pimples (though I'm not quite sure what exactly they are). Also, the skin on my outer thighs is covered with many dark spots. The hair on my outer thighs grows haphazardly, and hair growth is not even. There are spots where only stubs of hairs are growing, interspersed between clumps of centimeter-long hairs. What should I do to remedy this?

Exfoliate, exfoliate, exfoliate! I assume waxing the hair will help as well - wax it once, then in 3 months time, wax it again. It will even out the hair growth and help to exfoliate the skin too.

Anything I can do to prevent ingrown hairs after waxing? Or do I just exfoliate regularly?

You can use a chemical exfoliant like TendSkin. There are other products like TendSkin as well.