Re: Exercises away from the kit that work for you.
If I'm stuck waiting on something and I'm seated (waiting room, desk, etc.), I like to do quiet coordination exercises. I've improved the timing of tons of things this way, and used it to specifically build up a lot of freedom in my left foot. Here's two ideas:
Run a pattern in one set of limbs, then do Stick Control style stuff with the other set. So maybe singles between your feet on the floor, then doing double and paradiddle variations with your hands on a desk, arm rest, your knees, whatever. Then switch it up: how about doubles between your right hand and right foot, and variations between the left-side limbs. Do as much as you can - in my experience, all the mental focus and neural-pathway-encoding transferred over to the kit easily, and it just took a little working up to play the stuff with some feel.
The other idea is to set up grooves between certain limbs and then play melodies with the remaining one(s). This is like the New Breed, if you've done anything like that. One thing I got a lot out of was playing typical rock, r&b and jazz grooves with my hands and right foot, and then working through as many rhythmic and melodic ideas as I could think of with my left foot. That opened up so many little tricks and options for me - my left foot can be very active now when I need it, and it feels so natural thanks to all that away-from-the-kit practice.
Hope you have some success with it too, totally recommend it!