The children can be A positive or B positive but not O or AB.
A
The father's blood type can be O, A, or B.
No!
A+
Blood type is a combination of the mother's and the father's genes.
A positive with highest probability
Yes.
Yes, as long as the mother has B in her blood type (either B or AB), the father can have O.
Yes.... because blood trait A is dominant on blood trait O... the child will then have blood group A
ab+ a+ b+
Yes. If the father were BO+ and the mother were AO+, there is a 25% chance their child could be an O+.
Yes, it is possible for both mother and father to be RH positive and a child to be RH negative.