Tyler,
When in doubt be sure to keep a copy of the CRL printed and handy.
The back of the TK armour is essentially three pieces: The back plate (OII), the kidney and the butt plate. So yes, you would separate the kidney and butt plate, but then later strap them together.
The front is two pieces, the chest plate and the Ab/cod. It is NOT recommended to cut the cod piece to make a "TK brief"
There are so many different strapping methods, I trolled tons of build threads and EiB and Centurion threads to find various strapping recommendations that worked for me. What I chose to do is have a connection from my upper Ab to my upper kidney plate that goes over each shoulder, so it is suspender like. Honestly, once I have everything on, I am not sure that strapping is actually doing anything. It will be a bit of trial and error and I am sure there are lots of recommendations you can get when you ask around.
Good luck with the continued research and build and feel free to keep asking questions. Many AP kit owners on these forums to assist with any AP specific queries..