Hi Matt,
Congrats! The MD80 is very quiet in the flightdeck. Headsets is mandatory nowadays, but when I started flying this plane we didn't use them and it worked fine. During engine start you will have to open your sliding window to hear it actually starting! Noise level when airborne and normal speed regimes is so low you can speak to your colleague in a normal tone.
Hand flying - keep it properly trimmed and it is behaving nice.