Does all box2d bodies have collision detection?

Question

What I want to know is if both b2-static and dynamic bodies have automatic collision detection.

And how do I tell box2D what it should do when it collides with a specific body?

Answer 1

You should follow some tutorials as you are learning Box2D. Every body in Box2D has collision detection unless disabled. There are many way of checking collisions, here they're explained well:
http://www.iforce2d.net/b2dtut/collision-anatomy

Also do some research please, things like this can be easily found on Google or even here.