Hello, first time poster, short time lurker

I'm up in MN looking to setup a system similar to wolfracers. I'll likely be going with a 150 gallon tank to raise tilapia and/or yellow perch. I'll probably end up going with about 5, 20 gallon grow beds, and i'm liking what i'm seeing with the loop syphons that wolfracer setup. Here are where my questions come in to play.

1) I'd like to have the beds gravity fed, and only need to use a pump to take water from the sump back to the fish tank. Is this feasible?
2) With a 150 gallon tank (probably filled with ~135 gallons), is it best to go with a round tank, or one of the rubbermaid stock tanks from somewhere like tractor supply?
3) What should i be doing for a flood/drain schedule in a system this size? Do I need to have less grow beds, or a bigger tank to feed the number of grow beds I have?
4) I'd like to go low-power on the pump, and am thinking of going with a DC EL-SID10B12 pump, which runs off of DC. The downside to this, is that with a 30" lift, I'd be limited to about 2.5GPM flow.

After typing all of this out, I realized I'm really wishy-washy on all of this at the moment. I'd be open to any suggestions on what type of system to put in a 10x12 greenhouse.

I'm excited to get my system put together, thanks for any help I can get.