I'm not sure what you mean by this but as for blood type, there's no reason two parents with different blood types can't have children. The children would have AB or O type blood depending on the recessives of the parents.
no
yes
yes they can
of course.
yes
Sure.
Barack is type AB, so there are several possibilities: Mom A, Dad B Mom B, Dad A Mom AB, Dad A Mom AB, Dad B Mom A, Dad AB Mom B, Dad AB Mom AB, Dad AB
You could potentially be: A Positive B Positive AB Positive A Negative B Negative AB Negative
If a dad is O+ and the mom is B+, there is no reason for the baby to be born unhealthy, at least due to blood typing.
A, B, or AB, positive or negative
You could have several children with different blood types. you get your blood type from either parents or even grand parents.
Since O blood is recessive and B is dominant, this scenario would be possible