* Number of students: The French Ministry of Education publishes statistics on student enrollment in public and private schools at various levels (primary, secondary, higher education). The total number is in the millions. You'd need to specify the level of education (primary, secondary, higher education) to get a more precise number.
* Number of staff: This includes teachers, administrators, and support staff. Again, this is a large number in the millions, spread across many different schools and institutions.
* Number of people who enter a school building daily: This would include students, teachers, staff, visitors, and possibly parents. This number is highly variable depending on the day of the week, time of year, and the specific school.
To find the information you need, you should specify what you mean by "get in" and the level of education you're interested in, and then consult the official website of the French Ministry of Education (Ministère de l'Éducation nationale et de la Jeunesse).