Grace begets good works so there is no contradiction.
I don't think it is sinful if the child learns. I believe it is if the child is misdirected by the adult. Under this environment then you know my answer and it is closer to Vichy than you'd expect.
I care about MGM because I realize what it has caused me and my (legal and female) partners.
I'm not a priest but I'm studying theology. My education is not over yet.