Ref post 1351. I recall the H2S being driven by a 112v DC supply, a legacy of the Lancaster(?). No hydraulics at the front end of the beast.
Regarding stopping PFCs for practice, IIRC the limit was 2, and numbers 1 & 3 were generally used because they could be restarted first in the A & E sequence. A bit more physical when landing with both off, but not unmanageable!
Ray