Can you have multiple skill builds? For example, when you are max lvl can you have a PvE build and abruptly switch to a PvP build without having to respec?
Nope. 2 different weapon slots for 2 "sets" of active skills.
I believe (not sure since i don't use any) that there is a mod that allows you to "auto-equip" being off-combat whatever weapon/skills you save (like a macro of some sort).
If you like playing the game as is, then no.