Got it working now .... yay!
The registry problem, after everything, turned out to be a typo ... duh!
I was loading the hive to PE-SYS and the .reg files were trying to merge to PE_SYS, so after fixing my load command, the merge was applied successfully.
Having copied the appropriate .sys files from my system32 folder (although I noticed the sysWOW64 folder had copies as well), the app still was complaining about the device driver not being available. A little search on google informed me that the sysWOW64 folder had the 32-bit version of the drivers and the system32 folder had the 64-bit ones ... yep, that made sense to me.. NOT!
So I copied over the files from the sysWOW64 folder and it is now working!
My next step is to create a simple little gui with 3 buttons - Paragon Backup & Recovery, Easeus Partition Manager, and command window.
Thanks so much for your help!