The answer to your first question is this:-

When you select the "3 point lighting" preset your are essentially opening a scene file. With this in mind it is better to open the "3 point lighting" preset first then delete the two rocks (theses are just for display purposes). Once you have deleted the rocks then import the object or objects you want to use from poser via the "Content" tab.

I also agree with what GKDantas says. It is easier to load the naked model into Carrara then cloth directly within carrara via "Content" tab

Hope this helps..