Everyone basically covered what you need. One thing i noticed that wasn't mentioned by many was the NEED to sign up for Apple's DEP Program. It is a lengthy process to sign up, but worth it in the end. It will allow you to create non-removable profiles on the iPads to retain full control of your devices at all time. This will also allow you to create VPP Accounts, as well as creating student accounts for students under the age of 13 (Apple requires you to be 13). Other then that, a very strong IT Team, a Great MDM Solution (AirWatch / JAMF Casper Suite) [those were my top 2 choices] as well as caching servers and strong WiFi. Also something to think about is if your ISP Provides enough bandwidth, we had a problem once we deployed our 12,000 iPads with maxing out bandwidth. This would cause our PoE Phones to stop functioning creating a safety issue that needed to be delt with ASAP.
Also for 1:1 program, you would want to filter your students at home.. Our solution was to have the students forcefully proxy back to us so we can always restrict content as well as monitor and record sites.
As for saving data, 1:1 the student has the same iPad daily (for us) and can save everything locally. Our Students not in the 1:1 program but in the cart based 1:3 deployment (cart rotates to different class rooms), students could use Google Drive with our personalized Google domain to upload any files they would like to save and continue working on.