I'm just getting into drum maps. And already I'm frustrated. When setting the in/out notes, you seem to only be able to set these with MIDI note numbers instead of pitch names. Is there any way to specify a pitch, e.g. G 3, instead of its note number? 

I think so.
 
If you double click any of the notes whilst in the drum map it should open up a smaller dialog box where you can enter all sorts of information.
 
I'm not at my DAW (shame) but from memory I believe this is the case.

The drum map manager in the preferences shows the note name in braces. The drum map in PRV has an option in the context menu to toggle between displaying note number or note name. But input seems to be note number only.

Yep, input seems to be note number only as you say. Including the "map properties" dialog. How ridiculous, does anyone else find that to be a major obstacle when working with drum maps? Do they expect us to consult a chart of note numbers? You'd think that in 2015 we'd be able to enter note mappings by pressing the key on the keyboard, or at the very least displaying that actual note name. Seems like an area crying for improvement. 

Add your name to the long list of us calling for drum map interface improvements. You've only scratched the surface with the woes of the drum map interface. Great concept well overdue for a bit of TLC.

This is one of the main reasons I just don't bother with drum maps anymore.  That, and the fact that all the numbers are two octaves off of the numbers in Battery (which also uses notes names).  
 
On a side note, I would love it if the PRV could change to show the drum map style - note hits, but not durations.  That would make it nicer to edit drum parts in the PRV.