I have a question about Session Drummer 3 and the instrument/program loads and one about additional drum sounds
 
When I use one of the drum programs that come with producer, I get sounds beyond the standard kit, which is  what I have experienced in the past with other programs and I’m guessing there is a midi general drum map in play
 
When I look at the individual instruments I see 3 - 5 possible  sounds  assigned to different midi note values and these are usually closely related to the what I guess you could call the primary instrument.
With a cymbal, it might be a bell hit, with the hi hat, it’s the possible variations, open, closed, pedal etc,
 
 In some cases, I can get the some of sounds with the indicated midi notes, but not always.
 
However here is my first question. If I load a different snare into one of the drum program/kits, I lose the stick hit. Is there any way to get it back/avoid this issue?
 
Also, has anyone purchased any of the other sets of drum sounds the Cakewalk store offers or ones from any other sources that they liked?

It all depends on the the sfz files that define the instruments. Sfz files are text files that can be created/edited with any text editor. Create a custom sfz file with the parts you want.

Thanks, it never occurred to me to edit the files!

are you loading the snares sfz file or the flac file?
choose the sfz, not the flac when loading files into session drummer unless they are custom drag and dropped samples.