Thanks for all the helpful advice!
I think you're all right as regards the creamy sauce. Buffalo mozzarella isn't quite right for the job, plus the flavour is too delicate.
As for the stringy chunks, well...they always seem to join together, into one giant cheese lump when i toss them into the pasta.They don't stay separate and evenly distrubuted. Perhaps this is pure coincidental bad luck! I will however try the suggestion of allowing the pasta to cool first and also try the sprinkling as a topping idea too.
Once again, thanks to everyone.