I've heard people talk about it before, but how many items can you fit in a library folder? Do you just create new folders and move things when the limit is reached. Does P5 make this process easier?

256 in P4/PP. There's no direct way to create new folders which are accessible during a Poser session. A compromise is to move things to other, under used folders (camera, face, hands, lights) and rename the file extensions accordingly. The best solution is to use PBooost. P5 has better library management - but comes with some delightful "features" of its own, I'm told.

I'm thinking of doing multiple poser installs, since I'm dragging stuff into Vue anyway, might solve some of my problems to do one for settings and one for just human models etc. Marque

Get PBooost. It will be the best $20 you ever invested for Poser.

P5 has good organization. There are other problems (some fixed with service packs) but I can not go back to P4/PP because of the huge mess I would have with folders.

I have P5 too, but I keep going back to PP4 because of it's simplicity. I keep packing in my new stuff inthe PP4 runtime library so I know where to find things. Plus I have some python scripts that won't run in P5. Not to mention the walk designer in P5 still doesn't work. Eventually I'll get the hang of the new features in 5, but it's nice to know how people are organizing their stuff.

You can add more file folders in ProPack, at least. I've changed my character directory to better suit my needs (merfolk here, robots there). You can't do it while you are actually inside Poser, but you can certainly edit and move stuff while it isn't running.