We were just at WDW Nov 30-Dec 5th.
My son is 2, will be 3 Jan 24th. He was slightly over 40, and we took him on everything but tot (which he insisted he wanted to ride but I said no

)
The only ride he had scare issues with was Splash. When we were on it "I don't think I can do this" and after "I don't ever want to ride that again"
I didn't want to take him on Splash, but the rest of the crew insisted he'd like it...Mom knows best...
I think BTMR is fine, no real dark/loud noises.
We didn't get to ride Soarin, (did a late start and did TT instead, hoping to squeeze it in when we go back in October.) but as long as your son isn't afraid of "heights" I think he'd be fine.
If he is used to rides, I think he'll ease right into these!