I have been designing architectural floor plans in AutoCAD for the last 30 years. Back in the eighties a bunch of us started working with a dealer who wanted to develop a way to automate AutoCAD to be more than a drafting tool. For $495 we got a tablet overlay with all of our wish list on it. Every month we would come to the Hartford User’s group with our ideas and would receive a updated version of the software with all of the new Lisp files. Eventually the set of routines were put into AutoCAD as their Architectural Package. This is the package I currently use but I really think it is time to move away from this package since Autodesk introduced Revit and has pretty much abandoned AutoCAD Architectural that has not been updated in 10 years and is very difficult to work in 3D.
I want to know who is doing BIM work in SketchUP and what extensions you would recommend to help with the process of take-offs and presentation rendering.
FYI, I changed the topic title to “Take-offs and presentation rendering for BIM work”, as the questions you asked had not much specific to do with what it was before, … (“Floor plan components”, etc.)
Although the opening paragraph is nice (to know where you are coming from and what you are initially expecting from SketchUp,) this kind of introduction belongs in your profile’s “About Me” box, or you can copy it over to a new post in the “Introduce Yourself” topic thread. It really doesn’t contribute to the topic, and is a distraction. (Ie, it violates Occum’s Razor with a bunch of unneed fluff. Modernday translation: “Get to the point and stop wasting ink.” 
)
There have been previous discussions on these subjects.
Search the forums using the main search page:
http://forums.sketchup.com/search
… on various buzzwords. “bim” “rendering” etc.
You’ll find most of the discussion on external rendering extensions, in the Extensions category.
BIM is usually discussed here in the Pro category.
“Take-offs”:
Have a look (or search) through the official SketchUp blog: