I've just got a couple of relatively straightforward questions because I don't have the books on hand to check, and even though they are on two topics, I didn't see the point in cluttering up the reference desk so I've chucked them in here together.

Do we know how the Lestranges got caught? I know it was after they tortured the Longbottoms, but do we know if they were caught at the scene or whether they were tracked down afterwards? And also, do we know who turned them in?

Do we know or have any hints as to whether Rabastan is older or younger than Rodolphus?

And finally, did the Dementors go over to Voldemort during the first war?