If interest is a factor, then yes, your chances improve by touring, assuming they register your name. It's not really mentioned on the CollegeBoard page for College of Charleston, but I'm sure it can be a tipping factor if they're deciding between you and another candidate.
Definitely do Early Action (submit earlier and you'll automatically be listed as EA) since CofC is somewhat rolling admission.
CofC likes out of state students, so that could actually help you, especially if they need more Maryland people.
Continue to show interest and do your best in school from here on out