Cover image and sheet adjustment

Hi guys! 

I have 2 questions 
So. As a graphic designer I am creating a quatation template for my client. I can send you an excel file.
Question N1 : do excel has an option to create a proper cover, or I just have to insert an image directley to te sheet ?
Question N2 : can I lock ( not freez tool ) some of the inserted images and also vertical section lines, that my flient could only add horizontal lines but not mess up the desing.

Thanks a lot in advance!