1. Blake has access to the heating and wiring schematics.
2. There is large generator outisde the facility (marked as area 25 on the map). It has its own control room on the map (see room 23). One could reach it by walking outside, but this is not necessary - the two buildings are connceted via a tunnel.
That sublevel contains a circuit breaker room (27 on the map), located directly beneath the power control room.
The facility is heated with a combined oil/forced air system, which has its own controls, located in room 24 - adjacent to the power control room in the outbuilding. Note that the ducts in use are relatively small, so there is no possibility of people crawling around in them.
Finally, to round out the utilities (even though you did not ask), there is a water treatment room in the sublevel (26 on the map), located adjacent to the circuit breaker room.
3. Conceivably, one would shut down the power from the power control room, yes. Unfortunately, this is not the movie
Jurassic Park, in which invincible computer data protection schemes are bypassed by simply turning off the computer.
I'm operating under the assumption that one of Blake's first actions was to do a cold boot.
4. The disks play back fine, but appear to be recordings of dull, mundane events. They are dated, and the catalog is more or less constant, though there are a few small gaps.
Noticeably, there are no disks for a period of time of about a week, during late 2023.
Also, the machine itself was empty when you arrived. There are no disks labelled for any time earlier than six days ago.
Of course, you haven't more than afew minutes reviewing the disks so far.. there's no telling what you might find. If anything.
Note that the recordings seem to be of laboratory activity only.