I've been following a bit as well as your DS sounds very similar to mine.
Just on the pram thing. My DS too would settle heaps easier if I took him out shopping aswell because he was in the pram he would nod off without the usual screaming before hand.
We are now on holidays for 2 weeks and I was stressing because we wouldn't have the glider chair with us and I was concerned about getting him to go to sleep.
However since we have been away he has been an angel! No dramas whatsoever and it's because we only have the pram to get him to sleep. It's been bliss he is sooo settled by just popping him in the pram when he gets grumpy.
Maybe try bringing the pram inside and see if that gets him to sleep. I had been hesitate to try this at home, because I was fearful of it not working while we were out, if you know what I mean, but so far so good.