1. Yes, if you find any oversight, report it and I will add a translation.
2. There is no maximum size, you have to decide what size you want the logo to be.
(By default, the maximum height of the logo is set to 80px, after uploading it will reduce the size of the logo to this value)
3. There are special settings in the template settings, you upload the image you choose, and the link to which it should redirect.