Here's what I see from the Hytera programming software.
Wow, that's a mess of federal, amateur radio and public safety frequencies. There's the real possibility of interfering with others there.
As others have said, those radios look like they were never programmed and someone just took them out of the box and started using them.
Reprogramming them so you are not in violation of your license, and not interfering with others, should be priority #1.
Step 2 should be to talk with your administration and figure out what they want to do, and specifically what their budget is. With what you have, you can reprogram those radios to be legal and use them simplex right now. That may be sufficient for what they need.
The mention of the repeater raises some concerns. If no one knew it was there, it's probably been years since it has had any sort of preventative maintenance done. If they are going to want to use that system, contact a local radio shop and get them to come out and look at it.
One thing I'd caution:
The school will look for the cheapest way possible. They'll likely let you do all the work. Unless you have some experience with this sort of stuff, it can all go sideways really quickly, especially if they are going to rely on radios for any level of school safety/response. Don't be the one guy that gets thrown under the bus when things go wrong, just because they want to save money.
Relying on a hobby radio site like this one for support of a radio system is not a good plan. You sound like you have some interest in this stuff, and that's good, but you need a professional to help get things fixed right now. Hobbyists are not the right people to be trying to help you design a radio system over an internet forum. Get the school/district to properly fund this so you don't catch the blame.