My question is what happens to the BoS after finishing the quests, whether you side with them or destroy them. If you side with them do vertibird encounters continue in the wasteland. More importantly, if you side against them does the same thing happen but they are enemies? My priority is to have the biggest variance and numbers of enemies for the end game, and if that requires turning on the BoS then I'd rather do that.

Second question is do legendary quality higher tier armours exist as random drops? I've got some fall damage reducing leather legs that are tier 2 of 4 in quality, but other than that I have 100 legendary armour pieces now and they are all tier 1 so their DT is worse than drops from just about any enemy. Note I am not talking about unique legendary named items sold by vendors. They can be higher tier but regardless seem to not make complete sets (devastators, commando, black ops, overseer to name a few)

I sided against the BOS. Afterwards, you still get the occasional BOS raiding party and Virtibird attack, but not as many as when they were still an organised group.

If you side with them.. I dunno. I sided with the Institute, and I see Synth patrols going around sometimes, but hardly anything to speak of really. After main quest it's mostly Gunners, Raiders, Supers and Ghouls doing the nasty. Which is a bit disappointing really, I wanted to wander the wastes with my Synth Army crushing everything underfoot muahaha. Maybe a DLC will fix that. Or a Mod.