Yes.
yes
If all the children are AB, then one parent is AA and the other is BB.
No probability. Neither parent has an "A" for the child to inherit to make an "AB".
Yes. Blood type should not be a factor in who you marry.
When talking only about marriage itself, a man with blood type AB can marry a woman with the same blood type. However, when talking about having children, having different Rh factors in the blood can cause fertility issues.
The mother is genotype AB, the father is either genotype BO or BB. If the father is genotype BO, the children can be genotype AB, AO, BB, or BO. This results in children with phenotype blood types of: AB, A, or B. If the father is genotype BB, the children can be genotype AB, AB, BB, or BB. This results in children with phenotype blood types of: AB or B.
The mother is genotype AB, the father is either genotype BO or BB. If the father is genotype BO, the children can be genotype AB, AO, BB, or BO. This results in children with phenotype blood types of: AB, A, or B. If the father is genotype BB, the children can be genotype AB, AB, BB, or BB. This results in children with phenotype blood types of: AB or B.
The mother is genotype AB, the father is either genotype BO or BB. If the father is genotype BO, the children can be genotype AB, AO, BB, or BO. This results in children with phenotype blood types of: AB, A, or B. If the father is genotype BB, the children can be genotype AB, AB, BB, or BB. This results in children with phenotype blood types of: AB or B.
The mother is genotype AB, the father is either genotype BO or BB. If the father is genotype BO, the children can be genotype AB, AO, BB, or BO. This results in children with phenotype blood types of: AB, A, or B. If the father is genotype BB, the children can be genotype AB, AB, BB, or BB. This results in children with phenotype blood types of: AB or B.
An O positive girl may marry an AB positive man. There are no blood-type related restrictions on marriage.
AB
The genotype of the man is A negative/O negative inheriting the A neg from his mother and O negative from his father. [Father's genotype is B positive/O negative. Mother's genotype is B positive/A negative.]