"How was your (birthday) party? I hope it went as well as you'd hoped." That's one way, at least, but a bit formal. You could informalise it and say "I hope your (birthday) party went great" (She is American, so "great" is ok).
Well, your choice of words reflects how close you are to a person, same as French I guess. Perhaps, from what you say, something like: "Was everything cool (meaning go as planned)", and "did you go out anywhere?", meaning restaurant/club/bar etc - that should cover it.