How long has fight night round 3 been out for on ps2 and is there going to be a fight night round 4 on ps2 ??

Answer 1

Fight Night 3 was released almost a year and a half ago - February or March of 2006.

There hasn't been an announcement about FNR4 on any platform. If you're deciding on a game to buy, I'd get the 3rd one because my guess is that we're at least 6-12 months away from seeing a new version.