7.1 side surround speakers ....can they be too high on the wall?

My room doesnt work as well as i would like for the side speaker placement. I can place the side speakers close to the ceiling on the walls and i'm now wondering if thats too hig? The speakers are 1ft in length and will come a few inches off or from the ceiing b/c of a door and window on the side walls.

Any thoughts?

I'm also running a long sub wire for approx. 50ft, actually less but always good to have enough slack. Any thoughts on the best subwoofer speaker wire and does it loss signal strength with a run that long?

Thanks

That too, proximity to the rear speakers, was a concern given the room dimensions, 13x19, and where I have to sit, approx 12-13 ft from the screen.

Any thoughts on a long sum cable run? Equip will be in the back of the room so sub cables has to go up 1 wall into the attic, across the room (20ft. Approx), then down another wall and then over a few feet for center placement.