I don't have an answer to all of your questions, but I can aswer a few.
2. Yes you can, there are more datails in the student handbook.
3. Not positive, but I'm pretty sure it transfers over to the new major. But you have to pay a $50 fee to switch it.
4. The courses you've already completed that are required for both majors should transfer over to the new major, but if you've taken any classes in your current one that are not required or cannot be used a elective credits in the new major then you may end up having to pay extra for a few classes down the line.
The student handbook should tell you who you need to contact and give you the number. Since I'm not 100% on any of this my advice would be to check there and call to get a definite answer to all your questions.
Hope this is at least somewhat helpful! Good luck!