Is this position legal?

Congrats MARattigan! You did all versions - by SpiderUnicorn and by me. And you nicely protected the bK from the wQ check by placing a knight on f8. That is the sort of stuff real retro-problems are made of!

Wait, I mean

I don't see why it wouldn't be, making a proof game however...

Edit: I've got it, it's very inefficient but here it is:

Edit: Done it again - damn!

Here’s a much shorter game.

Thanks @SpiderUnicorn! However, I did find another solution without the White rook moving at all.

@Arikstotle - Had me going there!

Are these legal?

First on isn’t legal, second one is.

Interesting question about the 2nd diagram of #2269. Which black move leads to checkmate in 3 moves?

Yes. This gives the specified position (as opposed to just the specified board layout).

In the previously posted solutions the castling rights and (except in one case) the ply count under the 50 move rule didn't match the FEN specified.

I think I have figured out one method! It takes 13 moves.