Definitely--because the embryo will be fertilized and implanted into your uterus, having your tubes tied doesn't have any bearing on the situation. Go for it!
Yes, with gestational surrogacy. The surrogate carries the implanted embryo and has no biological affiliation. Since after tubal ligation your uterus is intact, you can be a surrogate.
It is possible even though you have had your tubes tied that they may come untied and you could get pregnant. There is a slim chance of that happening, but it is possible.
