Sure, no problem
1) Yes, I was on track for a green card within a year or two, but when I resigned I it was abandoned
2) I had some very nice friends who brought me some bags before I left Canada
3) The Canadian side of the border was immensely nicer. They tried to give advice, and let me back in after I explained what happened. The biggest difference is their demeanor. While the US people were extremely hostile from the start, the Canadian counterparts were nice and courteous. Talking to US officials was like being in a real interrogation, after this I'm much more sympathetic and get very uncomfortable watching people get interrogated on TV cop dramas etc...
3) Many reasons. Let me just also mention that we don't have children yet. Firstly, we felt our life would be better in Sweden in terms of work-life balance and family life. Especially having a family is much easier with longer vacations, maternity/paternity leave, heavily subsidized child care, socialized healthcare and a general safety net if anything goes wrong. Secondly, we're both immigrants, her being Chinese, so immigration would keep being a problem for many years, more so for her I think. Third, just like you, I have family and friends back home, which also adds a safety net, and of course I've missed them a great deal. Fourth, we're looking forward to doing traveling in Europe, there's just more to see in a smaller area, but that's not a major reason :).
All that said, we both had great jobs, earning probably 50% more than for the same job back home, while cost of living is lower in the US, and we don't have jobs lined up. The US is just great for having a career, and there are more numerous and interesting jobs in our fields, so it's not easy leaving that behind.