To clarify your question, no actual "plate" is used here. The slide is cut to fit the footprint of the Shield RMSc, which the Sig RomeoZero also shares. We provide screws for both of these. The HS507k may fit, the depending on the tolerances of the specific unit in hand. The screws will need to be shaved if you go with the latter.
Yes it is compatible with the P365 and is cut for the Romeo Zero
The Grey Ghost Precision Sig P365 Version 2 Pistol Slide is cut for the Shield RMSc optic footprint. So any optic that shares the RMSc footprint will fit, such as the Sig Romeo Zero. This is a P365 compatible slide, so you will need to use P365 compatible iron sights.
Both Versions will work with current production P365 grip modules and internals EXCEPT you will need to order an old style extractor. We stock them on our website: https://greyghostprecision.com/p365-extractor-old-style/
Yes it should function on a SAS grip module.
Optics are not included with the slide. It is compatible with the Shield RMS-C and the Sig Romeo Zero.
Old Style extractor.
Yes according to Sig a P365 slide can be swapped onto an XL frame.
Not if the barrel is ported (compensating holes that vent gas upward)
Unknown. While the gen 1 507k shares the footprint, we cannot guarantee drop-in fitment due to the large varying tolerances of this optic. Some handfitting and custom length screws may be required.