Wow! Lots to deal with. We experienced a lot of these things with our second. He was a super preemie, so was being watched closely for muscle tone and delays. When he was young I hadn't heard of OE's and just assumed that all of his quirks were from being a preemie. Like Grinity's son, he had OT when he was young and it helped a lot with sensory issues. If he qualifies for any reason for the OT I would definitely take advantage of that. I still to cut tags out of shirts until he was at least 10 and even at 12 he's very picky about which socks and pants are comfortable, but the few months of OT made a huge difference in his ability just to live in his surroundings.
He slowly grew into being able to remain calm with a normal amount of noise (he started at the click of a coffee maker turning off in the next room). He found classical music when he was 5 and has enjoyed that in the background.
He has never become a good eater - but this probably is because of being a preemie, not because of OE's, or maybe some combo. Having read every book about feeding/eating issues I could find, I would definitely follow the advice of others here and not push the food. The fewer conversations and struggles you can have about food, the better chance of growing up with a good relationship with your food.
And also to repeat others, sign language was a tremendous help. I certainly never learned a lot, but the ability to communicate with even a few words calmed him a lot. When he started talking he was calmer, when he started walking he was calmer. I think he was a little person stuck in a body that wouldn't get him what he wanted.
I don't think there are a lot of kids this extreme. I also had people tell me that I needed to "help him adjust." The OT did that, but I couldn't have done it alone - and it didn't help for people to imply that somehow if I just did things differently, he wouldn't be acting this way. So, give yourself a break and say "WOW, he's really something."
He may always be extremely sensitive, but he'll change from what he is right now. That is a guarantee. Don't let the pediatrician be too relaxed about it all. She may not really understand just how sensitive he is. Life is never dull, is it?
