Re: disc brake
What you should be doing is getting an 8" front disc rotor and Avid BB7 brake caliper and front caliper mount.
The rear brake is the last thing you even think about when it comes to making a fast and controlled stop.
Would it be logical to say that when braking hard with front and rear brakes and when all the weight transfers to the front wheel, taking all weight off the rear wheel, that the rear brake is doing nothing at all.
Under hard braking, the rear brake has virtually no effect and when the rear wheel is coming off the ground, the rear brake no longer has any influence on stopping the bike.