Any reg can fit on any gun, and work good, as long as it can be screwed into the marker's vertical adapter (right in front of the trigger frame). So, yes, a Vertical Max-Flo can fit on basically any marker.
Ya, it probably wouldn't hurt. Just you will still get the same effects that Co2 has, like marker sweating, etc. Plus you may have to clean your reg more because of the Co2 since it is a pretty dirty gas.
But keep in mind that switching back and forth with Co2, and HPA isn't a good idea. Try to keep it mainly HPA.