1.) David michelinie. As a huge 80's comics fan, Michelinie was never my all time favorite writer or anything but the guys good and you gotta give credit where its due. This guy wrote iron man for a very long time and a lot of the characters identity is thanks to him.
2.) I'd say maybe warren Ellis for his Extremis, short but sweet.
I never read any of Denny O'Neil's Iron Man but I have read A LOT of his other stuff such as Batman\Spider-Man and I always loved it so I have no doubt his iron man was good.
Fight takes place at a Mexican fiesta. Its around 8:30 est, weather's cloudy with a slight chance of meatballs. Venom is hungry and Namor is buckass naked and cocky as ever, with his big ol ding-a-ling hanging down to the floor (it literally touches the floor). Who wins?