Schools do not have any access to your information until you add them to your My Colleges list. At that point, they can see only the information you have filled out for their school. They cannot see other schools to which you are applying.
Any schools listed in My Colleges will have access to the following information from your application: Prefix, First Name, Middle Name, Last Name, Suffix, Preferred Name, City, State, ZIP, Country, Ethnicity, Sex, Applicant ID, Citizenship Status, DOB, Entry Term, Decision Type, Applicant Type (First Year or Transfer), Academic Interest, Paid Status, Recommenders, School CEEB and School Name.
If you permit schools to communicate with you prior to submitting an application, they will also have access to Address1, Address2, Home Phone, Cell Phone, Fax, Email, SSN and IM Address.
Once you submit an application to a school, that school will have access to all the information on the specific application.