Thanks guys. Bruce, my "critical path" (highest PD) as I plan it right now, will be a straignt run, ~26-27 ft of the acoustic flex (if I can get it) pulled mostly straight, with the boot, and a wide radius 45 and 90 (turn up into trusses, then perpincidular to trunk) from a round trunk at the source end. If I can find anyone around here to build a ductboard trunk in this one room section I will, but so far I don't trust any of them to do it right. Duct board is unpopular around here for whatever reason, not knowing how to do it right is my expectation.
For the other branches, I'll have PD to spare so adding some bends shouldn't be a problem, but I'll run the PD numbers for them to be sure I stay well below the worst run. I'm going to us a VS blower, and I want to keep the PD as low in it's range as possible so it stays more quiet, too. AC coil eats about 0.1"wc, I plan to make the returns wide open, can have too little PD there as I underrstand it.
I need to introduce some makup air so I need a good filter to clear the allergens for the fam, as we all have them. Blower willl do it's required CFM from 0.1 to 0.5". I'm still working on the media filter choice, but they appear have high loaded PD's even at 600CFM and merv11.