Teensy downgrade questions

I have been researching this for a while but I haven't been able to find any clear answers.

1. If I power the Teensy via USB then will it have enough power going to the NOR to flash the chip without plugging the PS3 in?

2. If I power the Teensy via the VCC on the PS3 then can I just connect the PSU and leave everything else unplugged?

3. Will the board/chip be ok (grounded-wise) if I read/write the downgrade without reassembling the PS3?

I am concerned that the wires (26 gauge I believe) will shift and snap off during reassembly so that is why I would rather flash it before reassembly.

Thanks in advance for any help people can provide.