Does AutoCad now draw from support files for things like layers and linetypes, text and dim styles, etc... the same way Microstation V8i does, or is it all still contained within the template file?
The layers and linetypes, text and dim styles are saved in the template; however, definitions for drawing new hatch patterns are not (they are in the .pat files) and font definitions are not (they are in the .shx files).
That depends. Linetypes are (still) defined in LIN files, hatch patterns in PAT files, fonts and shape files in SHX, etc.. Text and dimension styles, and layers, are not externally "defined" in that way. The settings which define them are stored in the drawing files.