New MacBookPro query re keyboard remap


I just got a new MBP to replace my beloved 2008 version, and I love the speed but I sorely miss the Enter button. Is there a way to remap the keys to make the Right side Option button an Enter button or is there a key command that will act as enter? The Return key does in some apps but not all and not in my email program. And why would keyboard light work intermittently? There have been a few occasions when I need it and it is locked off, only to come on again a short time later.