I don't have drums so I use AD/AD 2 to create drum tracks. I thought I would try tapping on a microphone or something to get a track that I could use DR on to augment or replace particular drums pieces. 
 
I held a microphone in my hand and basically clapped my hands to get the transients. The transient levels were all over the place (amplitude wise). I thought adding a compressor would help even them out while retaining some dynamics.
 
Don't I have to destructively apply the compressor somehow though?
 
Is process effect the only way to do it? If so, does that mean I can't use the Pro Channel compressors?
 
Thanks

You could export and re-import the track, I suppose.
 
I've had the same thought you seem to be having; it would be nice to be able to use the Drum Replacer post-FX. I don't think that's how ARA works on a fundamental level, though.

Bounce the track or freeze it and drag the frozen clip to a new audio track. Either way will product a new audio clip with effects applied.

I was thinking freeze was for synths. I looked up bounce but I thought it was for something else. I will give it a try. Thanks!

Freeze essentially does the same thing as bounce+archive within the same track. It is not just for synths. You may notice regular audio tracks have the freeze snowflake between Automation Write Enable and Archive buttons