1- OT Vader wins if it is in a setting where he can use the terrain and knowledge of Anakin to his advantages. On a flat Setting, ROTS Vader would beat him.
2- OT Vader, hands down.
3- OT Vader has armor and one solid hit will bring down his younger self. Plus OT Vader has shown himself to be quite proficient at using his body to fight (http://www.swtimeline.ru/?comics=79&page=043 http://www.swtimeline.ru/?comics=79&page=043 , http://www.swtimeline.ru/?comics=128&page=027 )
4- OT Vader only improved... Plus he doesn't need goggles.