A campus visit is just you visiting the school, watching a game etc. and this is unofficial.
An official visit that is initiated by a coach, then they are interested in you. They can pay for you to come visit in this case. Details are on NCAA website.
You can go on as many unofficial visits as you like.
If you cannot make it on an official visit because of your various HS life commitments then just be honest with the college coach. Virtual tours are readily available but an on campus tour is the best.
Schedule visits around vacations, tournaments etc.
Follow up of official visits with a nice thank you to everyone from the college who was involved in your trip.
Parents - Let your child manage the visit themselves. Do not control the conversations via email and on campus!