How high is my chance of getting infected with MRSA while visiting in a hospital?

Small. Wash hands before and after visiting with soap and water amd you will dramatically decrease your small chance of getting infected. This is same advice given to health care workers ho rarely become infected with mrsa.
Low. Low unless you are not careful to wash your hands after or you touch infected tissue. If you spend all day just talking to every patient in the hospital and wash your hands - there is no chance to get mrsa.