The previous contributor submitted several good resources for you to review. I'll give my two cents on some of your questions. I am a Senior Civil CAD Designer. (using Civil 3D 2022)
1. Should I have the drawings and the layouts/titleblocks in the same file or should I create another file for the layouts/titlebocks only with the drawings xref into it? The answer to this question solely depends on the company you work for and its practices. In general, titleblocks are their own drawing. They are xref'd into other drawings.
2. If I rename the layouts would it update automatically the list name in the sheet set manager and vice-versa? Or would I have to d it manually? if it is supposed to be automatically mine is not updating, for some reason. When using the sheet sets, the use of Fields is mandatory. At a bare minimum, the sheet number and sheet title will be sheet set fields. The "Rename and Renumber" option from the sheet set menu govern the renaming of all your sheets. They are additional options within the Rename and Renumber dialog box that would also re-label your drawing layout tabs as well, if you want.
