and another thing....why does the handbrake only brake only the back wheels and not all the wheels?

Separate front and rear circuits....but on a KE20 all 4 corners are connected

To tell you the truth, I have no idea. But it does, and that's all that matters :) Something to do with the design of the master cylinder (it's not the same sort as you would find on the front of your firewall, it has an "input" and "output", instead of a reservoir and an "output"