1)yes it's a 3.5mm
2)yes u can...
if im not mistaken if u use direct control or ipod adpter to connect to u'r ipod,u control the ipod from the HU, and if u connect from aux-in u can't control the ipod from the HU
3)maybe u can ask those sifu in audiophiles section to DIY the 3.5 connector,cos last time if im not mistaken some of them selling those good quality DIY 3.5 connector