The alien who resides among you shall be to you as the citizen among you; you shall love the alien as yourself, for you were aliens in the land of Egypt; I am the Lord your God.Ummm, yeah, only most had to wait 4 generations before they could become members of the congregation, some had to wait 10, and others could never become members for all eternity. The primitive Hebrews were many things, but they were not assimulationists--rather they were commanded to jealously guard their cultural identity (Full disclosure: I'm Jewish.) Hence: many of those they displaced, they destroyed.
You are absolutely right! In Ezekiel, there is a whole chapter devoted to the men who had children by alien wives. In order to keep Hebrew blood pure, they were instructed to put the women and children in a place outside the city and the fathers were to care for them but not live with them and not have any more children with them.