What or why do I have to pay for 'site fee', 'ceremony site fee' and ceremony, and officient? What is the difference?

Generally there is some charge (or requested donation) for the site where the ceremony is held (a church for instance) and almost always for a reception site. There may also be janitorial charges. The officiant is the person who performs the ceremony - a minister, priest, rabbi, judge, etc. They are also generally reimbursed for their services. EZ Wedding Planner includes these charges in the Budget. If they do not apply to your wedding, simply delete them from your budget (or change the amounts).