Another question related to brakes is this: On all aircraft, when I
run the engine(s) up to full power, the aircraft starts sliding
forward even with the brakes on. That doesn't seem like a very
accurate simulation. Is there a way to control that?

SNIP

Go in and edit your aircraft config file for better breaking results
but be gentle grasshopper.

I would be gentle if I could find an "aircraft config" file, but I
have looked at every menu and sub-menu I can find in X-Plane v7, but
there's nothing resembling anything to do with brakes. Of course, I
can't say I begin to understand much of what I am looking at: clarity
of purpose is not one of X-Plane's strengths!

Bob