I've been doing some reading and noticed that both the Heavy Armor and Light Armor trees have set bonuses if the armor you wear matches (all elven, all orchish). Does this only apply when you're wearing ALL peices of the set, or just some and no other peices?

You have to be wearing the four pieces. Armor, helm, boots, gloves. Ebony is bugged and doesn't give you a set bonus.

thank you. Guess thats one perk I wont take advantage of.

They don't all have to the from the same set though. If you wear say an elven helmet with a glass body it still counts. You just need to be wearing four pieces. This also doesn't count for shields. So you can have a heavy armor shield wearing light armor and still get the bonus

this is where i wish we had a hide helmet option and to the smart arses that say we do, im not talking about an animal hide helmet or not wearing a helmet.

I would love a "hide helmet" option!

PC users: Google "Skyrim No Helmet Mod". Works for me.

-Loth