For the size issue:
Other issues, start here: STL 3D questions
In the Cam Bam forum, go here and look through threads on 3D, especially those started by Imagining: CamBam - Index > Problem dxf files etc...
Also you've run a lot of questions into one questions, and it makes it a bit confusing to understand what you are after. Then again, it just may be my fuzzzy mind!