@shinCH,
Other than a few t-tests, what you really need here are histograms. For questions 1-3, all you need are histograms showing the distribution of the variable. For 4-5, you can use a simple t-test with a histogram of the each variable (for example, a histogram of mastery of basic math skills for boys next to one for girls). For 6, a simple x/y graph will work, maybe with a least squares fit if the data suggest it.