American University- History, economics, political science- which school at AU?

I know a high school junior who is beginning to look at colleges. Mostly he has been attracted to small liberal arts colleges. He does not know his major yet but is mostly attracted to social sciences and thinks history, political science, economics, psychology or philosophy may attract him- especially history and political science.
He is intrigued by American but a little confused. Here are some questions not cleared up by looking at the school’s website. There is no political science major in the school of arts and sciences, but there is one in the school of public policy. But that school lacks the other subjects that appeal to him. Does one apply to a specific school? In other words, would he need to settle on a major before applying? Do students transfer schools if they start at one but then decide to major in something at another? Is it possible to take classes at different schools? Is there a limit on the number of classes one can take at schools other than the school where your major is?
Thanks to anyone who can help address these questions.

Any major chosen by an incoming freshman will have no actual impact on what classes they can take or whether or not they can change majors. You apply to AU as a whole and not for any one specific school; so for example, I entered AU in the School of International Service but have decided to switch my major to Public Health which is in the school of Arts and Science. I can easily change my intended major without having to jump any hoops because you don’t actually declare a major until the end of your sophomore year.

The only thing that actually matters with your intended major is that it determines who you will receive advising from. If he entered AU as a PolSci intended major, he’d receive his advising from the School of Public Affairs but if he entered an undecided major, he’d receive advising from the School of Arts and Science. But overall, this doesn’t matter much because each advising department can help you with a schedule or any other problem.

Thank you!

@TheGreyKing also, if he wanted to major in political science AND history or something in a different school, it is very possible to have a double major across two schools within the university

Thanks!