Ewa Beach is in the middle on no where. Literally. Its on a coastline far, far, far, from Icon. Almost complete opposite in fact. ICON is solid but like I said its far, far, far, far from your location. Traffic in your new are of EWA is absolutely terrible. You going be in traffic more than in training if you thinking of ICON.
As far as other MMA gyms, you got two or three closer with 808, Jesus is Lord and Westsider MMA. 808 and Jesus is Lord are in Waipahu which is like 15 minutes from Ewa, very, very, very close. Falaniko Vitale, Ron Jhun train there, Westsiders in new but they got some tough guys. Lot of guys have good striking in these gyms since most boxed or street fight since they are from poorer side of the islands. Ground game is improving and the transition from boxer/streetfighter to full mma schools has come along into its own style.
Other informational sites you might want to consider is run by Relson Gracie Black Belt Mike Onzuka and his brother Chris Onzuka.
Welcome to Onzuka.com Pretty much anything happening in Hawaii these guys got it on their website.
Good luck.