I need advice on Dissimilar runs using XLR

I have a tri-amped system where the 2 SS amps are very close to the speakers. I need to make 2 runs to the SS amps from the crossover. One run is 1m the other run is 6m. All my components are balanced XLR in/outs.

My questions are:

1) Will unequal lengths of XLR make a noticeable difference between the L and R channel? and;

2) I’d like to get the best value for the buck for proper interconnects, so what brand do you recommend and why?

3) What are the problems (if any) of using 2 different quality brands with identical metals. (I may buy single cables used)

Anybody can pop off $3000 for a set of nice cables, but I’m searching for value. I’m good with used.

ARC SP15, ARC VT130 amp, Morrow 4 interconnects, Bryston 7Bsst2 monoblocks (for the woofers) Bryston 10B X-over & Model T speakers. Sources vary- Rotel CD, HD with hi res rips, computer, retired the phono- deteriorating vinyl wore me out but I do have a unplayed Slim Whitman album in reserve :)