/diy/ - Do It Yourself

What advice might you offer me on finding replacement transistors? Tell me if I'm wrong on any of the following and post your choice databases.

I've heard that Ueb, Uec, Ucb, collector current, and transition frequency specs can usually be exceeded.
I have also heard both that hFE can be met approximately in either direction and that hFE should be exceeded. What should I do for that and why?
Outside of the obvious polarity, power dissipation, and outline, is there anything else imperative to pay attention to?

Specifically I'm looking to use this in repairing the power amplifier of a stereo, if that's relevant.