About tenure... it is very important to know how important it is. I know tenure gets a bad rap, but there are two key things to remember about it.
First, it is very easy to get rid of a teacher who has tenure... just plunk them where they don't want to be. Sixth grade teacher you don't like? Drop them to kindergarten... they won't stay
Secondly, tenure is VERY important because without it districts would simply fire all teachers once they got any sort of experience. In a profession where there is no money being made, it becomes very easy for people to say "Well, do we want the $35,000 teacher, or the $70,000 teacher?" Far too often, people will believe that they should simply take the cheaper teacher to babysit. Without tenure, no teacher would stay employed once they gained some experience... districts can be ruthless when trying to get rid of experienced, "expensive" teachers.