Sherwood Schwartz answered #10. There is no mystery. Carol’s first husband and the father of her kids was Roy Hinkley, also known as ‘the Professor’ on ‘Gilligan’s Island’ (another Sherwood Schwartz show). The story was told on ‘A Very Brady Sequel’ so it is canon.
Mike Brady’s first wife was Genie from ‘I dream of Jeannie’. We don’t really know what happened to Major Nelson, but, Schwartz also put it in “A Very Brady Sequel” So, again, it’s canon.
Well if the Professor was taking a day trip with Ginger and Maryann there was likely a divorce in the future anyway. I bet he engineered the thing, think of all the the child support he didn’t have to pay stuck on that island. Not bad at the very very least gets too look at Ginger and Maryann, and laugh at Gilligan. Too much coincidence that his schemes to get off the island always failed at the last minute.