VOX Amplug 2 Lead (AP2LD) Black

Q: what size headphone jack does it have?

Small, 3.5mm! Your regular iphone jack for headphones

Q: Does this model (AC30) have an overdrive / distortion mode? Trying to decide between this one and the "Classic Rock" model...

The ac30 does not have a distortion mode. What I love about this one is it is super clean sounding. I'm 100% sure you can buy a piece to go from it to a pedal than to the head set, but take it from me don't get there ac30 headset or any of the headset period with this. Buy a gaming headset, with a Mic. To everyone else sounds like your singing to no music, but sounds so clear to the user. Ac30 is better than I could ever hope for I recommend it 100% to anyone. Let me know what you think. XD