PLE not compatible with other versions: scenes created with other versions of Vue can't be used ( Vue4, 5, 6 ), but I'm sur freebie objects will load fine.
xStream is only useful if you want to integrate Vue scenes ( created with the PLE) into other 3D apps ( Max, Maya, Lightwave, Cinema4D), if you don't have any of these apps, then install Infinite.
Watermark/logo; watermarks appear all over the render. they blend quite nicely with the sky, but no so well on other parts. Logo appears at the bottom right corner of the render (Vue6 a new dawn)
Poser scenes import by using the object import command, like any 3D object ( there is a special Poser import dialog box afterwards, but it's pretty straightforward)