My DS (10 weeks) is exactly the same as yours, even down to the fast let down and choking. I was told by the child health nurse that they outgrow their tummy issues by around 3ish months which is when their tummies start maturing and coping better. I use infacol and infants friend, baths, tummy pressure, and bicycle legs to help with the wind. Fast let down has been an issue that has been difficult to deal with for me personally and I've tried all the feeding positions, I just found that he has been dealing with the choking/letdown better as he's got bigger (which is what I was told by the lactation midwife and the GP). A couple of times DS has had greenish poo too but I don't know anything about intolerances so I'm not sure about that (I did dr google at the time though and it said that it was pretty normal for BF babies? Not sure).