React-JS Loading components on top, and hiding specific repeating components

Hi guys i have 2 questions:

1, I cant higure out how to render my page always on top when the react-js route is updated its always render on the middle or some random position

2, I have the basic components in my app.js included header and footer thats the same for every page, but what if i dont want to show my footer on the main page how to hide it on that specific page ?