Help learning a new pump/filter/equipment setup

[7Sanders]

Taking over my friend's pool from the pool store and needing to learn about her equipment. Downloading manuals from the manufacturers, but not exactly sure on the valves in the plumbing etc. Any input is appreciated!
My guess: Valve 1 and 2 are the skimmer and the intake from the bottom on the jacuzzi part of the pool. Valve 3 must be the return to the pool, there are 2 jets in the pool (1 deep end, and one opposite corner of shallow end). There are also a couple of returns in the jacuzzi. Jacuzzi water is overflowing into the pool a small amount with this setup.

 

[Texas Splash]

Sounds like you've got the right idea on the valves and water flow from/to the pool. The Variable Speed Pump (VSP) has various setting for rpm, time, etc. Usually it can be on a low rpm most of the time unless vacuuming or mixing chemicals. For the sand filter multiport valve, make sure to turn the pump off before changing settings. When filter pressure increases by 25%, backwash. I don't use a heater, but it look pretty straight-forward. Just make sure the pH never crashes (below 7.0) to avoid damaging the internal heater core. If you have more questions, let us know.