WC, it is apparent that you haven't grasped the basic concepts using Poser.  I would strongly recommend that you read the reference and tutorial manuals which come with PP2010.  This is located on your HD where the Poser folder is residing.  Although, it may be a tedious read, the volumes will give you a comprehensive overview how to approach a meaningful and successful Poser workflow.

Also, be aware, some of the newbie questions you are asking have been answered before in separate, dated posts in the forum.  Use the search engine.  It is not the greatest, but it is functional. 

Another recommendation, until you become more proficient with PP2010, turn off Gamma Correction under your render settings.  Currently, you do not have complete understanding of it's function and how it influences your firefly renders.  Until such times, you are better off without it and it's frustrations.

To the questions, the easiest way to remove unwanted folders from the library is to use the icons on the bottom.  Highlight the folder and click on the '-' folder below.  If it is a runtime folder, then the removal icon can be found towards the upper right hand corner of the library.

No, you do not need to be online for the library to work.  You must allow internet access through any firewall or antivirus programs for the library to work, but it does not require an active internet connection.

To move models within your scene, first uncheck IK for both feet, and hands, if applicable, select the model, hold shift, and subsequently move the mouse.  IIRC, IK is found under Figure on your taskbar above.  Props do not have associated IK. 

Clothing come in 2 flavors, conforming and dynamic.  Conforming clothes are fully rigged for specific models and will assume the pose and morph shape when applied.  If you have problems with this concept, please respond in a separate post.  Dynamic clothing is best applied through animation within the cloth room.  Again, the clothing is modeled for specific figures, however this type is easier to dress a broader range of characters than conforming.  These versions are convered in the manual.

And just a matter of information, Acadia has put together a sticky post at the top of the forum which addresses most common tutorials, issues and instructions for Poser.  Peruse it's content, it may shed more understanding about how to done things better in Poser.