EF-Quad questions

Due to HOA restrictions I think my best bet for my first HF antenna is the EF-QUAD. But I have a few questions first. My office/shack is on the far side of the back of my house. I have a Rohn metal mast installed just outside the window to the backyard and I use a window feed-thru panel for ground, coax, etc. The metal mast is approximately 26 feet tall, with a 2m/70cm vertical mounted on top. I will feed all antennas through the window-feedthrough panel. The mast is grounded at the top of the mast to the bottom of the mast with 4 guage copper wire. The bottom of the mast is grounded with copper strap to a 10′ ground rod. Hopefully that sets the scene well enough.

– I plan to hang the EF-QUAD between the metal mast and a tree in the backyard. Can I do this if I put about 5′ of dacron rope between the matchbox and the metal tower to give some separation?

– What is the minimum recommended length of feedline coax? In this forum, someone responded saying 25′. If the feedline ends up being only 10′, what other options do I have for ground return? Could I ground to the earth ground I already have installed on the mast?

– I would like to also buy an 80 meter EndFedz. Can I also tie one end off at the metal mast and run it to a different tree? The two wires would end up going away from each other by about 25-30 degrees. I would only be TX’ing on one at a time.

– With the 80meter EF, could I hang the far end over top of the tree and let the far hang down vertically in an inverted L? If so, how far above the ground does the far end need to be?

Thank you!