As far as content is concern I have found external runtimes to be the easiest as when you upgrade or re-install Poser all you do is point the library at the runtimes.  Also makes back easier.  In my case all of my content is on a seperate drive (drive E) in a folder called Poser Content.  In that folder I have sub folders for V4, M4, Weapons Transport and so on.  How you arrange it is really up to you but external runtimes appears to be the way to go.

 

One very minor point, my folder used to be called Poser 6 runtimes, because I created the folder when I was using Poser 6.  This has never given me a problem whenever I have upgraded Poser.  Recently I started using Reality 3 and having a folder with 'runtime' in the name and with 'runtime' in the sub folders gives it issues.  Easliy sorted by changing the name but if you are starting from scratch and think you might use Reality, it might be worth keeping in mind.

 

 

I use Poser 13 on Windows 11 - For Scene set up I use a Geekcom A5 -  Ryzen 9 5900HX, with 64 gig ram and 3 TB  storage, mini PC with final rendering done on normal sized desktop using an AMD Ryzen Threadipper 1950X CPU, Corsair Hydro H100i CPU cooler, 3XS EVGA GTX 1080i SC with 11g Ram, 4 X 16gig Corsair DDR4 Ram and a Corsair RM 100 PSU .   The desktop is in a remote location with rendering done via Queue Manager which gives me a clearer desktop and quieter computer room.