The Revit API does not provide support for in-place families.
Standard and system family instances can be loaded and placed as you describe.
If you are new to Revit programming, I suggest that you first of all take a look at the getting started material and work through the step-by-step instructions provided by the DevTV and My First Revit Plugin video tutorials:
http://thebuildingcoder.typepad.com/blog/about-the-author.html#2
That will show you what other important material is available that you MUST be aware of, answer this question of yours, and many, many more besides.
Good luck and have fun!
Jeremy