How can I easily view the files/folders I shared and the ones that I shared with me?

You can view all the files/folders you shared and the files that are shared with you if you click on Shared in the Main menu on the left. The purple coloured icons mark the files /folders that are shared with you and the blue ones mark the files/folders that you shared with others. If you hover over the coloured icon, a text will appear letting you know which files/folders are shared with you and which are shared by you.