I can answer a few,
If the lovejoy uses setscrews and not clamps, then a flat would do you well.
Newer helicals use a clamping action that would hold very well without a flat.
My buddy Richard has a video showing how he loaded balls back into the ballnut.
Check out his other videos on installing the cncfusion kit.
The tension bar is almost always tossed for CNC, it limits the travels and isn't necessary.
"http://www.youtube.com/watch?v=cPOhAjmPADM"]YouTube- 34: Nook Ballnut loading