Motor/generator questions

Hi everyone,
       It's been a while since I posted here, hope there's still some
regulars.  I'm building a pedal-powered generator, mostly because I
can't stand using a regular exercycle that doesn't _do_ anything.

       Anyway, I've gotten to the point where I need a generator, but I
don't really know what to look for.  There is a junkstore nearby that
has a good selection of surplus motors.  What should I look for?  What
will indicate good efficiency when run as a generator in a low input
power range? (I guess that I can put out about 200 watts, but don't
really base that on anything.  Can probably do more for short periods.)

       Am I correct that if I run the motor in reverse at the same
speed it runs at on wall current, that I will get the same voltage and
hz output?

Thanks!