Yes, I made a few mistakes and I did realize I didn't need the whole extra bit to store 65 possible locations- I just was being a bit lazy. Ba dum tiss.

Hmm as a bit field followed by piece order- that would be 8 bytes followed by a variable number of pieces, perhaps you could do a sort of compression where 0c means pawn and 1xxxc is any other piece. (c stands for a color bit). So thats another 14 bytes. Thats 22 bytes!

The xxx by the way is one of 8 things: k, k not moved, r, r not moved, n, b, q, en passant pawn