There are multiple ways of completing many quests. The Pet Pal talent will open up additional quests and quest solutions, as well.
There are few dialogues that take attributes or abilities into account, other than the Charisma bonus for Charm/Intimidate/Reason dialogues.
There is a reputation system, though, and characters will treat you differently based on their opinion (can be raised with quests, trading or other interactions, lowered by getting caught trying to steal or moving someone's stuff, etc), the character's Charisma and sometimes equipment.
You can steal lots of stuff (Sneak helps, Invisibility is better), and get decent loot killing some NPCs (not everything they carry if they are a merchant, though, and not end game quality stuff).
