Bg7+ Rxg7,Qxi8+ Bxi8,Qxi8+ Kxi8,Ri1#
Is pawn b2-e8 a legal move?
No...the pawns pass from the blue squares as if they are classic
So from the initial setup, e2-e3 would make that pawn immobile permanently?
yes...that pawn on the 2nd rank is always a target through the bridges, but it may release from this position.