Ok, i know i can walk between T3 and T1, that's not a problem. I'm not going to use Flight connection transfers because i have a 6 hour layover and there's nothing to do in T1 when you transfer and are behind the security check in at the gates. I thought i'd get off and go through passport control in T3, hang out, shop, have a meal, then go over to T1 and hang out there. Then go through security again and to the gate. My question, after all that rambling, is do i have to go through passport control again as well as the security scanners if my next flight is a domestic flight?
We're also transferring in T5 a few days later, domestic to Euro international, but with hand luggage only so I expect that will go pretty smoothly.