In the OC you have absolutely no access to you companion's inventory. Their equipment gets upgraded automatically as they gain levels, but you can't give them anything yourself. This was changed in the expansions, allowing you to equip your companions yourself. As for spells, I'm not aware of any way to control what spells a companion learns (I believe this is all determined in their level-up scripts, with no way for the player to change it). I'm also not aware of any way to control what usable items companions make use of (such as spell scrolls)- from what I recall they simply don't make use of usable items, other than healing potions. As for looking at their stats I do remember there being a way, although it was a little convoluted; unfortunately it's been a while since I played so hopefully someone else can provide more specifics on that question.