You can use P4VS but a word of warning: it’s slow as hell and will lock up Visual Studio a lot if you have a solution file with the engine code in it.
For how your depot should be set up, consult the documentation. Your entire project folder should be kept in Perforce minus the build, ddc, intermediate and saved directories, if you are using your own editor build (ie. it’s from GitHub, Epic’s licensee Perforce or you have custom middleware integrations) then you should also include the engine files in your depot.