Drum Processing

and this is = to Rendering as stem in Reaper?

You're looking for "Apply Track FX As New Take" (or something like that). This will render your track FX onto another take within the same track, then you can manually offline the FX on that track.

I do it this way - there may be a better way, but this works for me - it's nice because I can delete the "effected" take and tweak, then reapply the erfects if I need to.

Pain because Reaper doesn't have a proper freeze function, but you can get around that with macros - go to the Reaper forum and search for freeze macros and you shoudl be OK. Or, make one yourself with the actions list.