Hmmm...if you really do like procedures, then fp may be the way to go.
As far as going IM, then pulm/critical care but only doing pulmonary stuff 20% of the time, people usually don't do that. The reason is after devoting 3 extra years to learning a subspecialty and taking a board certification exam to call yourself a pulm/critical care specialist, people usually don't want to go back to doing primary care all day. Also, primary care pays poorly vs. specialty care, so you'd be losing money (doing a 3 year fellowship as opposed to working at an attending job) in order to learn stuff that you'd only be using part of the time. As far as doing PFT's, you don't have to be a pulmonologist to do those...some general med and fp docs do those in their offices. Usually I think techs and nurses do them though...it doesn't really pay to have a doctor spend time doing that.
If you're really unsure about whether you want to do pulm/critical care vs. primary care, you might want to just go to an IM residency that has a strong pulm/critical care department at the main teaching hospital. That way your options are still open in 2 or 3 years (as far as doing fellowship or not).
You might be able to do a pulmonary fellowship (without the critical care component), but I'm not really sure. I know some people do straight critical care (no pulmonary) but usually folks don't do pulmonary by itself, as far as I know. Somebody correct me if I'm wrong.