Re: Concrete steps
I would not attempt to pull the steps out with a bobcat unless they are precast steps. To many times poured in place steps are attached to the house foundation with rebar and you can seriously damage the foundation by pulling them. The best thing to do is jackhammer them out, make the necessary repairs, and replace with precast steps.
As far as the repairs you ask about, generally you have to jack and support the outside wall and the floor joists in the area where the sill plate and rim joist are being replaced. Generally you only need to replace the bad section not the whole rim joist or sill plate but the new sections should be installed with a lap joint to the old.
Be sure you live your life, because you are a long time dead.-Scottish Proverb