Hello @Carole, Just go Configuration / SEO / Metas, you can include all what you want. Do not forget to change your seo inside product and other files, it's important to not have duplication inside your website.
Hello, The banner manager can manage your logo, but I think it must not too big. For me, the ClicShopping demo, for example is too big. If you have some knwoledge, you can use a tool like photoshop to change the image size, or you can use the image manager to make that.