Dragon Flight Paths (static map)

No, I’m pretty sure the light dragon flies significantly higher. Low enough to glide to from a launch tower, but some planning is required.

Theoretically yes, but you would have to be lucky enough for the dragons to cross paths at exactly the right time.... and like another commenter already said, the Light Dragon flies significantly higher than the others, so if you plan to hop from one dragon to the other, you'd need to ride the Light Dragon first, not the other way around.

PS: you can park a hoverbike on the Light Dragon's head, which makes the trip from one dragon to the other a lot easier. It doesn't work that well the other way around, as the other 3 are taking a nosedive when going underground - you'd fall off, along with the bike.

EDIT: See comment replies ;)

Yes. I once had the Light Dragon almost directly above Naydra. I got all the bits off Light Dragon, then jumped down to Naydra.

They get fairly close to each other at times. I’ve seen Light get a short glide of Farosh and Naydra before. I don’t really know how lucky I am but I’ve seen it about a dozen times and I don’t even hunt dragons; I just fly up to dragons the moment I happen to see them.

They were once close enough for me that I was able to glide from the Light Dragon to Dinraal with just about a single stamina wheel.

It no longer depends on the in-game time. The dragons won't come faster if you skip days at a campfire, nor do they show up at specific times. It is especially annoying for the Light Dragon as it takes her ages to complete a cycle, and you can only properly track her while you have activated but not yet completed a certain quest.