All depends on the RAM controller in question: if it doesn't like EDO, you're out of luck. Otherwise EDOs will work just as well.
If the RAM controller can take advantage of -50 RAMs, then these EDOs could actually run faster without making use of their EDO functionality. However, most old hardware has probably never been tested at that speed, so it's impossible to tell before you've tried.
And yes: the contact metal of the SIMM should match that of the socket. Mismatching metals form a galvanic cell that (very slowly) builds up an insulating oxide layer between the contacts, see
Wikipedia for details.
