Lets say I have a Vet Ultimates Hawkeye and I want to shoot at three targets with him. Would he devide his base 3 dmg or the entire 5 dmg.
Also lets say I perplexed or enhanced him up one more. Would I then be able to split up 6 dmg to three targets?
Thanks for any info.

You cannot split damage from RCE. You can Perplex or Enhance your base damage value (limited by Rule of 3, of course) and then split that up. The following is from the PAC:

RANGED COMBAT EXPERT. [RED] (optional) Give this character a power action. It may make a ranged combat attack against a single target. If this character does so, increase its damage value by 2. Ranged Combat Expert may not be used when using an object as a weapon.

Thanks thats what I figured.

If you declared multiple targets you can't use RCE.