How do the physical bodies of Jesus and Mary enter a spiritual realm that has no physicality, and how is the kingdom taken by force in Matthew 11:12?

Be careful what you mean by 'spiritual realm.' Your premise is that because Jesus and Mary have physical bodies, heaven cannot accommodate bodies, and that is false. Jesus now exists in a physical, glorified body, what Paul in 1 Corinthians 15 calls a spiritual body, meaning higher than the previous physical body, not non-physical. He still breathes, sits, and stands, so there has to be a real place there; and the same is true of Mary, Enoch, Elijah, and anyone raised bodily into heaven. God accomplishes their physical being there. As for Matthew 11:12, that chapter is about the Pharisees. They are the ones who take the kingdom of heaven by force, in the sense that they set themselves up as guardians at heaven's gate, inventing so many rules, over six hundred of them, that no one can keep them all, so they can point at anyone and exclude him, while priding themselves on their own supposed observance. Jesus calls them hypocrites, and in Matthew 23 he says they compass land and sea to make one convert and then make him twofold more a child of hell than themselves. That is what it means to take the kingdom by force: seizing it for themselves through man-made rules while shutting out those who deserve to enter.