On the garden situation. I would encourage you to research vertical gardening. Yes, I have the materials to make a lattice for climbers and will be installing 4 towers to each GB. Problem is so far my plants in the GB's aren't doing that great, either my PH @ 8.0 is still to high or my trees are shading it to much.

Why are we using a T and two intakes for the siphon stand pipe? With two intakes it allows more water to enter and fire the stand pipe. Plus with 200% water feeding your stand pipe instead of 100% it makes it almost maintenance free. With unrestricted water flow to the stand pipe it also increase the flow rate.

Yes, a 90 at the bottom of your stand pipe is fine...I have mine that way. As for the drain pipe enters your FT, I have two 90's connected together makes it easy to fine tune,

I was reading up on Chukar partridge, 2 questions will they cohabitate with my quail? It stated that they only lay eggs from April / May well into summer. My quails 1 egg per day almost 100% of the time, as far as size goes the only different I noticed was not color related. All my males are smaller then the females.