the answer to q.1 is wherever sounds best to you. every room has different acoustics, so what works in one room won't necessarily work in another.
as to your other questions, haven't heard either of your stand choices, but stands can have quite an effect on the sound. it may help you to get the heaviest stands you can that are 'mass loadable', fill them with sand or whatever, and this should help keep the bass tight.
in a small room the length of your speaker cable shouldn't have any noticeable impact on the sound, just try to keep them similar lengths.
mac mini + dacmagic, moon i3-rs, atc scm 19, atlas questor, atlas hyper 3.0, atacama avi, atacama hms2
i also have a chord company superscreen powercable.
but mainly cos it looks nice.
it doesn't make me a bad person.