larknz: To answer your first question only buildings that have multiple fire zones have fire doors. The average private residence only has one fire zone and therefore does not have fire doors.
Ahh because any kind of hold-open would defeat the purpose of a firedoor that must always be able to be closed or to close itself in event of fire. Of course that makes sense now.
I like the magnetic door stops, but it may make more sense for a front door to get a latch-back type that you can manually latch only when you want it.