Great questions, but we may need more information. What type of students and for what subjects? Are the iPads part of a school purchase?
There are many good places to find apps. Two I use are appshopper and appsgonefree. I also subscribe to the free email from Richard Byrne: http://ipadapps4school.com/
If you do a Google search for: sync ipads school you will see Apple Forums that will help you.
If you need further info, post here.