A)
Yes.
B) It should work but I've not tried it. I don't suppose it works as good as on the G2 powered by two SF123A batteries.
The
G2R is quite a bit longer than the G2. Personally I don't think it's worth it.
c) The B65 NiCad battery stick is part of the KR1 Rechargeable Kit for the G2, and part of the KR2 Rechargeable Kit for the 6P.
The difference is that the KR1 kit comes with the AN14 Body extender made of Nitrolon polymer. The KR2 kit comes with the A14 Body extender made of Aluminium and black anodised.
I personally don't think the B65 has the power to be as bright for as long as a pair of SF123As. In
this photo you can see how much longer the B65 NiCad stick is compared to a pair of SF123As. The Z29 Battery Spacer is used if you want to power the G2R or 6R (6P+A14) with two SF123As.
C) No. That I'm aware of there are no rechargeable 123A batteries that directly replace SF123A batteries in SureFire incandescent flashlights. The voltage of "R123A" rechargeable LiIon batteries is higher. Two should work in the G2 with the KL3 bezel attached. I have not confirmed, nor attempted this.
D) From my perspective the 6P does not make a good EDC flashlight because I need the flashlight to have a PocketClip. Also, the E2e is shorter and slimmer and weighs less. It is more idea for EDC. The 6P can be carried in a belt pouch or loose in your pocket. Personally I find this unacceptable. Too slow and too obvious.
The 6P and G2 are great bases from which to "build" a variety of SureFires. None in my opinion are ideal EDC lights for me.
I hope I have been able to answer you questions?
Al