Do I need to install SharePoint Foundation 2013 if I am going to Install SharePoint Server 2013?
SharePoint Server 2013 build on SharePoint foundation, that's mean when you install the SharePoint server it includes the SharePoint foundation in it.Just install the SharePoint Server along with all its pre-req.
In future when you install the SP, even then you dont need to install the foundation Service Pack, Just install the Server Service pack( which include the foundation bits in it).
No, you don't need to do that. The only thing you need to install are any necessary prerequisites.