First of all, using engine braking is the same as using the rear brake as far as braking forces go. Around 75% of your stopping power is in the front brake, however. Don't ever be afraid to use the front brake. Excersizes in parking lots help to get to know your bike in this respect. Some bikes (like my Guzzi) benefit greatly by the use of a little rear brake when entering a corner, for example. If you are locking up the rear wheel for any reason, I'm sorry, but you're out of control; either the ground is slick, something is wrong with your brake, or you're not using enough front brake to begin with.
Racing bikes have owners who ecpect to rebuild/fix things constantly, but speed and handling are their only concerns. It takes a lot of intensive training to understand how to ride like that and they still get hurt. I hear that tracks are "safer", but they aren't- they just have a different set of dangers. I don't have stats, but I suspect percentage-wise, there are actually more injuries on the track.
Personally, I use my front brake much more than my rear, and I shift constantly- using my clutch. It takes practice to get good at matching engine and gear speed when downshifting. I drive the throttle with my thumb while clutching, using the front brake alittle and downshifting (seemingly) all at once.
David Hough also has a couple of good books that I found were easier to understand, especially in a non-racing/real-world forum.
My 2 cents