Alot.. although it doesn't matter.. try researching this question on things like weight watchers website.
Hopefully, no more than 1 or 2 at the most. Depends on how fast you can drink them.
Your question is not specific enough. Can of what?
If you're on a low-carb diet than I don't suggest eating any sweets. However if you're referring to the natural sugar in fruit I would recommend about 2-3 servings a day. However, if you're planning...
A 1-cup serving of the original Cheerios contains 110 calories.