Step Sequencer clips: bouncing down to regular MIDI clip?

Never seen this happen but you could try opening the step sequencer clips in the PRV before the bounce. This will change the associated editor from the Step Sequencer to the PRV.

The Step Sequencer can do a maximum of 64 beats, with up to 16 steps (i.e., 16th notes) [corrected to 64th notes - see below] per beat.
 
The Step Sequencer is intended more for developing MIDI sequences, which you can then transfer over to the PRV. It isn't really designed to be a "container" for MIDI sequences created in the PRV.

Correct, I need a second cup of coffee . You can get up to 64th notes per beat when you have 16 steps per beat.

Man, 64th notes would be bar line madness to try to read.  Not at all practical for scoring.
 
Bob Bone
 

I know AD has the aility to edit drum maps, but I don't know how to do it.
 
You can use PRV to move the cymbals around and add the chokes.  You just need to know what note value corresponds to the cymbal choke.  There is a handy diagram of a keyboard and the associated drum triggers for AD in the AD documentation.
 
The other thing you could do, but its a bit more tedious, is break your original midi clip into smaller sections that do open in Step Sequencer and save each step sequence as a separate file.  Open each one, make your changes and then save them again, but that is an awful lot of work, just to use step sequencer when PRV really does the same stuff (it just doesn't loop it automatically).