For simplicity's sake, I still play 2-way checkback over 1♣-1♦-1NT. So 2♠ for me would be GF with longer diamonds, as 4♦4♠ would bid 2♦, or iow the NMF bid. After a NMF, generally the auction is forced up to 2NT. So if that was the case, if responder bids over 2NT then it's GF otherwise he could have just bailed in 2♣ or 2NT. This applies in the 3rd option where if 2♠ was F1, as 3♣ is too small of a target (could have passed 2N or rest in clubs earlier) and is looking for the best game.