Be prepared to wait but Justin is on here daily and will be attentive to any questions/concerns you may have. His products are top notch and hand-inspected by him personally. I can vouch for the quality.
AGD is actually fairly popular on the forums. Currawong recently reviewed a unit favorably. Dan can barely keep up and I cannot wish him more success, met him in person and he's good people with me. Jason rules, forever a Schiit fan.
The Rosewood had a few cracks but it has to do with Rosewood being somewhat difficult to work with and not any ineptitude. I'm sure after two years they have the process nailed and it was only a very very early issue. The bamboo was introduced because it was inexpensive, they used to issue a rosewood chest that came with the cans too before going with the Pelican case. Then they started charging extra for rosewood and here we are.
You can't. Double ended has less distortion since each amp will have to work less hard. You're working with SNR so it's less noise the less voltage you put through. Why would you need to ask us how to level your volume? Only you really know what your ideal listening volume is and people don't always listen to the same volume all the time. It varies with genre for me.