1. I think there's a good chance the cold symptoms could have been the start of mono. Mine started out like the flu, which really isn't much different.
2. There's only one way to find out, and I wouldn't recommend trying it! On a serious note though, I would suggest waiting a month or so before doing something like dancing.
3. Again, I would give at least a month before trying to get active with things again. I found this out the hard way, as I started working out again after I thought I was over mono, and then it hit me really HARD again and I had a major relapse. So in my opinion, don't take any chances; let your body recover a little while longer, and then slowly get back into your "regular" life. Best wishes!