I am not in commerce so I can't answer your faculty specific ones, but I have a handle on the rest of them.
Although it's good you're looking ahead into second year, you're getting too far ahead of yourself. What happens if you hate your courses, or do really poorly in one area? You're going to need to rethink your plans.
Also, not all courses are offered every year, and you're not going to always be able to get into the courses you want when you want.
Course requirements change every year, depending on when the course is taught (day vs. evening, regular year vs. summer school), by who, and what texts you need. If different sections have different professors, and they are occuring during the same term, they can also differ.
Economics is part of the faculty of Social Sciences, and thus not a part of the school of buisness.
If you have to take Econ 2X03 as part of your first year degree requirements that means you can take second year classes in first year.
However, as a rule (ie it is not part of your degree) I would try and avoid this. I took a second year poli sci class in my first year and was slightly overwhelmed.
McMaster's CA is based on a 12 point scale. a 5.0 is equivalent to a C, or 64-66%.
When in second or third year you can take courses for first, second and third year. In fourth year you can take courses from any year.
You are not accepted into a minor. A minor is something added to your degree upon graduation. In order to complete a minor you finish the components of it, and then you declare your minor on your graduation form. Otherwise it has no part of your degree.
If you have questions about your degree and are able to come to McMaster in July, I'd consider attending the Early Summer Orientation Program. You get advice from your faculty advisors on how to choose your courses, as well as attend other activities. More info:
http://fye.mcmaster.ca/esop.html
If you can't attend, I would suggest contacting the School of Business and talking to an academic counsellor there.
