I think your plan to take everything apart, put new O-rings, Oil, and Teflon tape is perfect to get it all back to its prime.
As for the bottom plate I’m pretty sure theirs no difference other than Tippmann Acquired more patents.
Before you do anything with the Cyclone feed I would fix everything else and test shoot it with quality paintballs. (Maybe the last time you shot it you had brittle paint) if it’s still a chop fest here a link to a video I found.
https://youtu.be/M13BcX19stc