Do I need to prepare the pipe ends before clamping?

Clean any rust, dirt, or scale from the pipe ends where they'll meet. A wire brush works fine. This ensures a tight seal — any gap or debris compromises the connection.

Will this clamp work on both steel and aluminized exhaust pipe?

Yes. The stainless steel clamp grips both materials. Just make sure the pipes are the same 2.0" diameter and seated flush where they butt together.

How tight should I crank down the clamp?

Tighten until snug — you should feel resistance but don't need to over-torque it. The clamp should hold the joint secure without crushing the pipe. Check it again after your first drive to make sure it hasn't loosened.