I'm not quite clear on your question: if it's whether the VCPD maverick in VC shoots, I don't believe it does. When police pursue/control the vehicle it does; however, this is an assumption that the passenger/riding-shotgun units are responsible for the weapons. When you fly... have fun flying. Vehicles which do fire are the Sea Sparrow and the Hunter. These are more available after many missions have been progressed.
Changing games, the VCS police Maverick (available easily on the roof of HQ once Ocean Beach unlocked) provides civilian radio broadcast instead of emergency chatter... I also don't believe it allow weapon use. My memory isn't what it used to be -- at least it might've been better... I forget. If you're looking for choppers that fire then, assuming you've got far enough to access the VCPD Maverick, just go to your safehouse [Clymenus Suite] and buy a Little Willie on the roof for $5,000... better yet, go back over to the mainland and find the Scrapyard. Look in the S.W. corner beside a dump-bin for a free Little Willie with no mission attached. The reason I say this is that many of these uncommon spawns (like aircraft) tend to have missions attached. An example of this is a Hunter that later spawns in Escobar that also shoots but has a mission attached. Someone over at GrandTheftWiki did an interesting piece on the helicopters used in the games, and these Police Mavericks had multiple versions within the games -- go look if you're interested (sorry, can't provide link at moment).
Concerning differences between police helicopters from different games, it's notable that the San Andreas P.D. choppers do allow some interactivity -- in that they're equipped with fully functional spotlights to use... still no weapons (again, that's for the fellow units onboard). Furthermore, if you get to the point where you can access Las Payasadas in Bone County (Las Venturas area), there's a two-player rampage that uses the police helicopter (one player controls the flight while the other does the firing).
Didn't mean for this to go on so long, but I tried to make up for uncertainty about the exact question.
Hope it's helpful. Vice City rules!