A Few Questions From an Undergrad

I am an undergrad student at a liberal arts college and want to get my MPH afterwards. International health is what I want to concentrate in and I do not plan on getting an MD. I want to be a health educator but feel that I will want to get into administrative work when I am older. I have volunteered at a foundation that funds medical care, education, and development projects in Haiti. On July 10, I will be leaving to study abroad in South Africa and with the help of the university, I have set up an opportunity to volunteer at an Aids Prevention and Care Clinic. I have a 3.2 GPA and will be going into my fourth semester of college. However, I have yet decided on a major! I could either switch to a state college that offers a BS in PH or stay where I am and major in a social science. This is a list of the majors I am interested in: Latin American Studies/Spanish, Psychology, and Sociology. These can also be minors along with Business Administration, International Studies, Pre-Law, and Anthropology.

1. Probably any of these majors would be beneficial but what do you think would be the best for me?
2. Do you think I should work a year or two before going for my MPH?
3. What do you feel about the Peace Corps MI/Fellows programs?
4. How are Loma Linda's, Tulane's, and UCONN's MPH programs?
5. Any other recommendations or advice would be much appreciated.

Thank you.