[Q] What can I do with Root without installing a new ROM? topic

So I'm pretty happy with Lollipop as a whole, but there are just some things that I'd like to change, and I'm curious if I can do it with just root or if they are ROM level features.

So the main two are, softkey change (I want the back button on the right) and activating the LED.

I'm sure there are a couple other things, but I can't think of them right now.