I haven't tried the 4-button remote so can't speak to whether it would work or not, though my money would be on no. I can say the 4th button would absolutely do nothing (I looked into getting one and trying to wire it to open the rear hatch or something). The receiver simply isn't set up to do anything with that other button's signal.
As far as general compatibility questions,
check out this thread if you haven't already, specifically the links I posted
in this comment.