I'm not sure about the requirement to continue filing US taxes - you only have to pay tax on foreign income earned in excess of something like $85K/per year . . . and if you are not working at all in Canada (as a visitor), you'll have no income to report. So, technically, even if you eventually had to file US tax returns for years you were in Canada not working (or not making enough to have to report), there shouldn't be any penalty.
And, yes, you can get Canadian citizenship without losing your US citizenship - although what Leon says is true. When you're dual Canadian/American and you are in the States, your Canadian citizenship is not "acknowledged". You're an American there - not Canadian. I actually had this conversation just last night with a woman in our church. She and her husband are Canadians - their children were born while they were living in the States. So their children are dual citizens, but when they go to the States, they are not considered Canadian nationals - they're Americans. As far as I know, though, when a child is born to American parents in Canada (as my husband's father was), Canada acknowledges the US citizenship as well as the Canadian . . . although it's really of no consequence either way.