i do believe that the latest iterations of trijicon do support external powering through a standard non proprietary jack and also have a some updated reticles but overall yes, they have dicked the dog for too long.
depending on distance to target..yes. the 27 has immense light gathering ability with the catadioptric 100mm lens and auto-gating intensifier tubes can handle going from dark to light filled rooms without issue.
Stick with anker power packs and youll be good to go. mAh doesnt matter. it is as you said simply longer run time. ive seen subpar power poacks cause issue many times.
get a rhino II . install the dovetail adapter and then run whatever j arm or bridge. i have the mod armory d14 bridge and think its perfect. others milage may vary but im not a fan of wilcox mounts for avarious reasons.
as to the nox working on a rifle, i use mine weapon mounted all the time...
If you're going dedicated go with a 50mm unit like the halo or mk3 etc. 35mm is lacking for alot of stuff. clip on thats worth its salt is nearly double the price of a scope and in general theres not much gain.