I also only have 8gigs on a PC and I am using Poser Pro 2014.

I use the fitting room on multiple figures which include M4, V4, Dawn, Sadie by 3D Universe and the K4 figures, so I am certain you can use any figure for the fitting room.

I have also used the Morph Copy on several different figures.  I have never used the PSD rendering..not sure what that is?? But the background rendering will render the current scene while you continue working on the scene which is a big help! I am no techy but I would bet that the reason your scenes are disappearing and the program quitting is because you are using a 32 bit system. Mine would do that sometimes when I had a lot of content in a scene. At that time tho I only had 2G on a 32 bit! Ouch!

Now I have 8G on a 64bit and havnt had that issue. My system is upgradeable to 16 G and I am getting ready to do that soon.

Yep! Save Your Files Often!! I learned that the hard way too! :)

Cheers!