One of teh biggest struggles I've had in pareting my J is figuring which problem is causing which behavior. And it seemed to change minute-by-minute.
So this is what I did, I started looking at his issues as marbles. Each one it's own size. The biggest one, I would work on until I could 'take it out of the bag' so to speak. I kept at it until at this point, three years later, I'm down to just a few marbles left besides the 'normal' kid marbles.
It sound's like the hearing loss is probably your biggest marble at the moment. If it were me, I'd focus on that for a while. If he can't communicate properly, then everything else will be very hard. Crick's advice in that area is second to none, really. She knows her stuff. Also, my son was 4 and developmentally 2 too. It's so hard to look at that giant body and remember that they are just a 2yo inside. I wouldn't worry about the letters and stuff yet. Focus on the communication and daily living and the rest will start to fall in to place eventually.
Blessings,
Jenny