So I made a Bosmer assassin who relies heavily on stealth, backstabbing, pickpocketing, etc. and I'm wondering if wearing armor hinders these skills in any way? Thanks.

I'm not completely certain, but I think unlike the future games, armor has no bad side effects (such as making stealth or spell casting harder). So if I'm correct, you should just try and get the best armor you can without worrying.

Armor doesn't affect your chances with any stealthy actions in Arena/Daggerfall, to the best of my knowledge.