I dont quiet understand the second question though what do you mean by first rank? Sorry for my lack of knowladge.
Rank means row. Squares a1, b1, c1, ... f1 are the first rank. A pawn moves backwards on its first move - pawn on e2 moves to e1. It is now on the first rank. Can it move two spaces? Personally, I would make the rule like this: "any pawn on the first or second rank can move two spaces." Otherwise, players must remember which pawns have moved and which have not.
Rank means row. Squares a1, b1, c1, ... f1 are the first rank. A pawn moves backwards on its first move - pawn on e2 moves to e1. It is now on the first rank. Can it move two spaces? Personally, I would make the rule like this: "any pawn on the first or second rank can move two spaces." Otherwise, players must remember which pawns have moved and which have not.