These are good jobs which usually pay well. Some school districts will put you on the same scale as the teachers, others may hire you independently. You may also be able to work for an agency which pays you -- the school district pays them.
These jobs usually have excellent benefits, including health insurance and pension funds.
Depending on your placement, you may be fortunate to be placed in one or two schools. However, if you work for a large public school system, you may be in many schools over the course of a week or a month.
Counselors usually work in high schools. School psychologists may work with children aged anywhere from 3 years (preschool) to high school. Both may meet with parents and teachers as well. A psychologist's job is to find out why children are having difficulties in schools -- usually involve evaluating or testing a student, observing in the classroom, interviewing parents and teachers, writing reports and/or behavior intervention plans. You may also do individual or group counseling. A school counselor often works with students seeking education after high school (most likely college or technical training) or within high school (vocational training). Counselors may or may not do group or individual counseling.
See program and course descriptions at universities offering masters programs in these fields.