Great subject. Make sure you're learning what you can about the scientific process and not just checking boxes. A publication would be great, but what's of greater value is for you to learn how to design and evaluate research projects. That will bear dividends throughout your whole career.
I wouldn't include it. Intentions will only help you if they translate into action, in which case you'd inform adcoms of the activity as an update to your application.
I didn't see anything in there about shadowing. You'll want to work in dedicated shadowing experience (which is separate from your clinical volunteering and paid employment) to directly observe the role and workflow of a physician.
On another recent thread, @gonnif wisely pointed out that you don't get bonus points for taking on a more challenging task unless you actually succeed. I recommend arranging your course schedule to maximize your likelihood of success on the MCAT. A poor MCAT score will do you far more harm than taking 14 credits instead of 17.
Apart from the shadowing thing and the obvious lack of an MCAT score at this point, it looks to me like you're right on track. Keep up the great work.