Most of what you've described is the same as my DS2 except that he doesn't spew very often and when he does eventually go to sleep, he sleeps well. I also put him on his side and never lay him flat. His bassinet and cot are both raised at one end which helps. He's 7 weeks today and I took him to a paed at 5 weeks and he was diagnosed with silent reflux. He's just started losec, a colic mixture (our evenings are a nightmare too), homeopathic drops and is seeing a chiropractor!! We're now seeing some improvements. The dummy helps him to continue swallowing as it's the acid coming up and burning his throat that is making him so uncomfortable. It's hard isn't it? Especially when they thrash around at the breast and cry so much. DS1 was an 'easy' baby so this is a bit of a shock for us.
Hope things improve for your LO soon.