I pray that all the transitions go smoothly, and that God provides for all your needs (as He usually does).
I have always been disappointed that schools give new teachers 5 preps, instead of just one to help them get their feet wet. As you said, though, it is a tiny Christian school, so they generally need people to teach many different things in order to even offer a full-time position. Fortunately, you are likely to have small classes, so discipline and grading should not be a huge issue like they would be in the public schools where you would be grading hundreds of tests/essays every week, and dealing with serious discipline issues on a more regular basis. For your first year of teaching, you can focus on classroom management skills, lesson planning, and content mastery.
My main tips:
1.) Get to know the support staff by name. They will help you get acquainted with the basics of life.
2.) Get to know the teachers next door to you. They can help you with emergencies (real or imagined).
They can also help you learn the computer programs for attendance and grades. They can also remind you that it is time for that meeting or that today is chapel day.
3.) Find out who has the same free period as you. These teachers will be able to give you the most help, since they do not also have to deal with their own students when you are asking them questions.
4.) Do lesson plans at least one week ahead of time. Remember that your administrator knows your plans may change, so you can adjust them after the fact. However, turning in the original lesson plans late creates unnecessary tension. If anything, going back to change your lesson plans shows your flexibility as a teacher, based on the needs of the students (so that's a good thing).
5.) Do your grading as quickly as possible. Students need feedback to bring closure to the lesson, but you also don't want grading to pile up.
6.) Use your free period wisely. Sometimes I just needed a breather after a tough day, but you need to get in the habit of grading and planning during this time. The more you do at school, the less you will have to do at home.
Feel free to email, PM, or post any other questions. The first year of teaching can be tougher than most imagine. But, don't give up! Ask for help! The rest of the staff is usually ready to help you when times get desperate. We were all first year teachers once, too.