Yes.
Does your husband have to legally and financially support his wife during a separation
yup
Yes.Yes.Yes.Yes.
The daughter being pregnant does not eliminate the responsiblity of a parent to support their child until they reach the age of majority.
If she is married, no. If she is unmarried, yes.
His daughter - probably. Her baby, no. see links below
Yes, child support and visitation and/or custodial matters are two completely different legal matters. All parents are legally required to financially support their minor biological or legally adopted children regardless of the circumstances.
No. She is still your child and still needs to be supported.
He is the father and not to allow him his child would hurt the child. Take him to family court for the support.
no
Yes, but if she gets married then you don't have to.
No. The father of the pregnant daughter has no legal obligation to support her child. That responsibility belongs to the biological father of the unborn child assuming that the pregnancy is not terminated nor the child placed for adoption or parental rights terminated by the court.