Drinky
These in a Leviton Brand are available at HomeDepot and have more flexability but here is a sample of what you can use.
http://www.parts-express.com/dual-speaker-wall-plate--309-125
Also look at these as an option:
http://www.parts-express.com/single-gang-reversible-bulk-cable-wall-plate-white--261-160
This would let you run one continuous length of cable and avoid 4 additional signal losing connections by using plug-in wall plates
2)Yes I would keep the length as close to the same as possible, but don't coil the excess.
3)Depending on the method you choose, always try to use the same cable from amp to speaker. Don't waste money on expensive cables for one segment of the run.
And lastly, I preface with:I am sure you are very happy, but thank you for reminding me why I am single....."just kidding of course"...it's just something happy folk do....more kidding of course.
Good luck, by the way the Tritons are way way under-priced for the performance they yield. I have heard most of the line and that company has raised the bar!