1. Just want to make sure, so you want the facebook like button become on bottom position?
2. Because the widget is wrapper with the menu item, so if you resize browser window the scroll bar will occurs.
3. If you want to change the side navigation become relative, you need change a lot of css code on certain element (make it responsive).
If you want to change the relative height on mobile menu, try to upload a small logo for mobile navigation.
4. Unfortunately, at the moment we don’t have those kind of feature. You can try to put it on footer area. And on desktop view you can hide those element by adding css code.
5. Try to follow this image bellow