Like BenH said, it's very impressive. However, I don't quite like the way tank's body 'vibrates' when you shoot. I don't think it's meant to do it. Also, the recoil is way too strong. Another thing that can be improved - there are gaps in the threads when the tank is over any sharp 'spike' in the terrain:
This is probably you have thread segment sprites look that like this:
You can try using differently shaped segments:
Other segments will cover those rounded ends, but in situations like that red 1 on the picture there won't be a hole in the thread.
I have no idea how to help with the problem number 2. Anyway, it's a lot less noticeable than #1.