Hi Kman42,
I have not done an ES kit yet.

However I have Gretsch Streamliner (hollow body with curve top) with a Bigbsy like yours. The 2 front screws hold the front part on the deck but the rest is sitting off the top.

As for the bridge pins - the only ones I have used have been very tight fits. But it may not be a problem for the tuneomatic bridge as the downward force from the strings will keep it in place. I have seen (On YT!) that wrapping one sheet of paper around the pins, covering them with glue, then inserting them into the holes is a useful solution if the pins are loose.

I assume the Tail stop will not be used so that should not be a problem.

For the G style nut - I have removed them from most builds by putting a small block of wood on top of the fret board up against the nut, then giving the wood a gentle tap with a hammer. I usually score the headstock edge of the nut first. They have always come off easily!

I hope this helps.