Yes you can contact the admission office of a university by simply sending them an email.Usually the admissions team of a university indicate their email address on their website.You could also contact them on their hotline number.
Yes, of course. In fact, it is advised to regularly communicate with the University, especially after you have been admitted. Ask questions, clarify situations, tell them about any personal circumstances that might affect your studying at their university, ask them about financial aid. Just speak to them.