-Yes, you can be an Archer/Thief/Assasin, you won't have any problem leveling all the skills you want, the only thing is that, as far as I understant, you have only 50 perks to choose, so if you pick the wrong perks you may get undermatched, but that's really hard since they are not 3, they're 50, and they're all usefull. -My main character in oblivion was the one you want to make now, it was a stealthy archer with mastery in alchemy, playing like one of these, I spammed invisibility (ilussion) a lot, because, I didn't saw much ways to hide in a tight passage (like in a dungeon), it was very fun anyway, you don't have to fight every foe you find, that makes you feel that you're "in control" of the situation, and, when the time to kill comes, you poison your bow with an "Extreme deadly poison" and watch your foe die in seconds, the main Idea of a stealth character is fight smartly and when you have the advantage, so you won't get the chance to fight 3 baddies, you'll just cloack yourself, get away, and search for a good spot for a kill, but if you're fighting them face to face, is all shooting and running, note that stealth hits deal more damage than common. -About the book thing, I don't know, I think you have to read them to pick them, if that's the case, just miss them, they aren't very priced anyway. -The Main quest IS the visit to the Greybeards, unless you go there you won't advance on the main quest, the civil war is a side quest.