1. He once invented a machine that could clean people so well that it was a fail.

2. His favorite chips are Cheetos.

3. The fangpyre venom never really disappeared. It's effects were just temporarily neglected. They appeared again after master Wu was lost in time. After that, Jay started wearing makeup to hid his scales, contacts to make his eyes seem normal, a wig after all his hair fell off, and dentures to speak normally. Jay felt that the Master Wu incident was enough, so that explains his choices.