I think the others have summed up your questions on males and females. I've never had a female but as Susan said, I have heard that the females tend to fight more with each other.
As for getting 1 or two birds, it depends. If you're looking to have tame budgies, 1 to start may be a good way to go. A few of us here have started with one budgie and later when they were tamed we added another - after having 2 budgies now I wouldn't keep just one anymore seeing how social they are. Even though my boys choose to be caged separately (my English budgie came with "baggage") they have both grown immensely since having a buddy. Taming can be much more challenging when budgies are in groups or pairs since they have such strong flock instincts. But most of us are finding out that it's all about patience. Dig around here in the budgie section and you'll read all about our efforts regarding one and two budgies and how things are going.
Good luck and let us know when you bring home a budgie or two
