Player Vs. Player is a different animal then pve. Yes, you can get by by just using a few abilities, but to be honest you will not be able to compete against someone that uses them all. The players that you see juggling abilities are doing so to be more effective. If I were you I would start with the main 2 toolbars and go from there. Remember that if you are clicking you are playing a different game then the ppl who are hotkeying. Clicking by nature has to be slower do to the fact that you are using the mouse to click attacks while others are using mouse strictly for movement and targeting. There are many guides that teach you how to hotkey without using a special keyboard and mouse.
I cant click anyways as I use my mouse to move not wasd or whatever so having to click would mean stopping. Also I dont plan on doing rated stuff so I assume I will be playing against fellow bads in normal PuG WZs. But out of the light saber classes which one requires least keys? Id at least like to learn my keybinds at a slow pace as I gain levels rather than getting slammed with like 20 abilities at a low level. Also Sage/Sorcerer doesnt count as they just have light sabers for stat sticks.