Hey Sweetiele,
Yes no problem, so for 1 you can almost do any exercise or drill that you would do with the ball as a shadow exercise but the best are simple ones that focus on footwork, for example 2 backhands 2 forehands. They just help improve speed and agility and also you can focus on technical elements without worrying about the ball.
2- Yes you can still hit through the ball woth a plastic ball, it just requires good timing as you said and to contact the ball in front of your body. I think using your legs and body and keeping a relaxed arm is even more important to generate power with the plastic ball. Try to focus on brusing quickly on top of the ball and imagine the feeling of hitting more forwards through the ball.
