Ezdrummer isn't something I've worked with, so hopefully someone else will pick this up from here. Still, let's see what can be done.

1) You probably need to be using ASIO drivers for this, not MME. Ask us again if you need more info on ASIO.

2) Sounds like there's a limit on the number of notes it will play at the same time (polyphony). There might be a setting for this somewhere.

3) No idea.

ROG.