I believe the question about "AC splitters" is related to what is more typically called a "Mini Split" system.  Its called "split" because it includes 2 units: one indoors and one outdoors.  Its called mini because the indoor unit is smaller than a typical indoor air handler (which includes duct work to move the air around to different rooms of the house).  Since the Minisplit doesn't have duct work it will only reliably work in the room it is installed, not multiple rooms.  I suppose one could install a minisplit in one room then use a portable fan to move the cold air around, but this might not work very well, especially if you want to close the door.

Yes they work well in small rooms, but make sure the installer does a proper heat load analysis to determine what size of unit is required.  If the installer doesn't know what a heat load analysis is then probably good idea to find another installer.  A system that is too big is nearly as bad as a system that is too small.

No they don't have a draft in the winter if installed correctly, It would require a very incompetent installer to create a draft, allowing outside air to leak inside the house, but there is no shortage of knucklehead installers running around.

I considered installing multiple minisplits but decided central air is better for my house mainly because it can include a really good air filter; Mini splits have a very rudimentary air filter, almost like a dryer lint trap, that needs to be cleaned more often and probably doesn't catch small airborne particles.  Any salesman that says a minisplit air filter is as good as an upgraded filter in central air system would need to prove it before I'd believe it.

Individual, per-room minisplits work very well for cooling assuming they are sized correctly, the best way to size the correct unit is with what the industry calls a "Manual J" heat load analysis.  Some areas building permit departments require a heat load analysis inorder to issue the permit, not sure about ABQ. 

-Bill on Solano