A drum map editor is just something that assigns certain keys to certain sounds on a drum machine. It's used when you load different drum machines into Cubuase, so that you can use the same keys on your keyboard to trigger certain parts of the kit. You'll still need the drum machine though.
Not sure about price but the basic drum machine for Cubase is the LM-4.
Can't remember if it comes with Cubase or not. There's also an upgrade called the LM-4 Mark II.
Best one is Battery, but hard to understand if you've never used one before.

You'll have to program them yourself or use midi drumfiles that are pre-written.
If you want to do them yourself, or edit them, you'll need a midi keyboard.
You can do it from the edit window, but it's a major pain.

Alternatively, you can grab some drum loops off the net and paste them together.