I think there's actually lots of factors that play into it. Mine do not have a "bedtime" like lots of other bird owners have for their birds. They get as many hours of daylight as there is, all year round. I don't cover them or anything either. I've even had pairs bonded enough for mating, still...
I've had up to 5 in a flight cage but that was out of necessity and ended badly. I wouldn't do it again. I currently have 3 in the large flight cage but having three is also generally a big no (I watch my birds' behaviour very closely and there has been zero issues, so far).
It's hard for me to...
Male or male and female pairs are best. If you're new to budgies I'd never recommend a female pair.
I keep mine in a "flight cage", they're very spacious and provide plenty of space for them. They're super active and will use every bit of the space you provide. When looking for a cage go for one...