Check my plumbing please

[LagunaGlide]

I am working on plumbing my crystalline G2 60x20. It has an external overflow with 2 drains of same height, and 1 emergency drain.

Here is my mock up of the drains. The white pipe will be replaced with black, I just happened to have some white for mock up of close enough size. My question on the drain side is, does it matter which one I make the “main” drain and put a gate valve on? I put it on the longer run because it was easier to fit, and could be easily mounted and centered on the brace.
How’s this? How deep into the sump should my main drain go?

 

[LagunaGlide]

I’m working on the pump side, and planned for 2 extra valves for expanion. I could add another, but I thought it would be important to have an equal number of valves on each side. So you can see my mock up manifolds below.

The issues I am having is that I have to off center it all to make it fit because I partitioned off 1/3 of the stand for a “dry” side and controller panel. My questions here are does it really matter if I put all of my “expansion valves” on one pump side if I have valves to adjust the flow?

Like could I just swap the hard line for the pump with the barb and the parallel taped valve to get the soft hose closer to the pump, or should I just add another 90 to that hard line to bring it so the soft line just runs straight up and down?

 

[LagunaGlide]

I decided to go ahead and glue all my down pipes. Haven't glued to Bulk heads yet. It seems I grabbed the wrong can for the ABS - PVC.

 

[LagunaGlide]

Bump?

 

[KStatefan]

Valve on the full siphon drain?

 

[LagunaGlide]

Valve on the full siphon drain?

Yes, but this overflow has two that appear to be the same height in the box. So not sure if it matters which pipe it’s on.