New Pool: Plumbing ....

[BMerrill]

PB says mid-late June install date.
FG 15.5'x40', 17,890 gal., 617 sft surface.
Eastern North Carolina.
Hayward system: OminLogic, Tristar VS900, SwimClear C4030, SWG-TCell 940, Pool lights, plumbed to add a future heater (HP or NG, 2psi meter 30' away)
Water features: 2 ledge bubblers (lighted), considering 4 deck jets or a simple waterfall. Waiting on quotes for these.

PB say he typical installs 1 skimmer, 3 returns, no bottom drain. Is this considered adequate?
From research it seems there should be 2 skimmers, 4 returns for this size pool.
On a side note one PB we were considering stated he has gone to 1 skimmer for all rectangle FG pools and usings 3" suction pipe for pools longer than 30'.
Your thoughts.........

4'x8' pad adequate for the pump, filter, and future heater?
Should unions be used so the valves can be removed?
Have seen some pictures that have a hose bib near the pump discharge and/or the heater. Are these needed?
Anything to consider to add in the piping.
Will have a flow meter, water temp, check valves, automated valves for water features.

Thanks in advance.
This has been a learning experience.

 

[Pool_Medic]

Two skimmers, 4 returns, if no main drain then I would go with Venturi skimmers.