I am attempting to enchance a person who uses energy explosion. As of the current rules, if I have 3 gotham detectives behind one of the swat guys who has energy explosion and one target...

1. Does the person who is hit by the initial energy explosion get hit for 4? 1+3 enhancement?
2. The target NEXT to the initial target, is the damage also 4? If not where would I find the answer in the rulebook? Or Errata?

No to all of your questions. If you read the power description of EE it states that the damage is determined by the number of times the character is hit. So...if your character has the ability to only target a single character then the most damage they could do to the target and any figs adjacent to the target would be 1 (barring a critical hit). If your character has multiple targets then each figure takes damage equal to the number of times it was hit (either as a primary target or by splash damage). The ability to use enhancement with EE was taken out a long time ago to prevent the ridiculous abuse that was IC Ultron.

Remember, though, that the Enhancement can still modify the damage value, although it usually has no net effect.

Say the EEer is Iron Man from SI and he's T-Bolted to Crusade.

He will have a damage value of 7. The damage dealt will still be dealt as EE normally deals it, but if he rolls doubles, the figures can be knocked back 7 squares.