When you marry someone, his or her family comes along as part of the package, and whatever family dynamic has been established. Things like your call screening policy you need to work out with your boyfriend, and as long as the two of you agree, it is up to him to deal with any fallout with his mother. You said that you have a right to have things your way in your home, but if he moves in, it will be his home, too, and you do need to make sure that he is comfortable with any rules you may have.

As far as children, that is absolutely something you need to discuss with him before you get married. But I would advise against making rules that are too stringent at this stage, like saying she could never be around your children. After all, you do not know how she would act around her grandchildren. My mother said some horrible, hateful things to my one brother's fiancee before they were married (she disapproved of the marriage), but my sister-in-law always treated my mother with respect, and she has since changed her mind. But if my sister-in-law had cut my brother and their children off from her, it would only have reinforced her feelings that the marriage was a bad one.

In-laws can be a burden, and you should do what you can to protect yourself from being hurt by them, but in the end, your boyfriend must be happy with whatever limits are set, since it is his family.