6' is probably fine if they all get along. 8' would be better, but I have 10 hens trying to stuff themselves on a 5.5' bar, so what do I know. :p If you end up adding more birds in the future, I'd consider adding a second roost at that point.
Many birds do seem to prefer a "window seat" and I...
That looks like it'll be a great set up for your climate.
I wouldn't worry about the neighbor's noise... chickens get used to stuff like that pretty easily. Had the generator outside noisily cranking away for 4 hours today and the chickens were still perfectly fine with coming out for a little...