For 1. If you are gone all day in library I would think it would be better to take BOTH at the same time so they are not sleeping all alone all day. If you were part time, say 4 hours work, then I would guess separate would be ok. But I would have them bonded FIRST before you start taking them to work all day.
2. We have a wonderful female that love people, we have a wonderful male that loves people and loves to explore a little more then the female. We have our original two males that are friendly. we have a skittish male and female.
In our second colony, the new one, we have two friendly females and one angry male that is getting friendlier and one small female that crabs alot with the male and is scared of us still.
In conclusion... I see no difference based on gender, only how well we have bonded with them.
3. I use OHPW diet with pet-pro "Happy glider" cereal in a side bowl. They are sold by Pocket pets as glider chow, and critterlove with the critterlove diet. They are said to be good at teeth cleaning and a healthy snack/food.