For a 5' deep tank you will have to use 1000W lamps no doubt. I use them on my 35" deep tank and have them on grow light movers. They only move the width of the tank and my corals love them. So much of what you plan is going to be determined by the space you are afforded that it would be impossible for someone to give you suggestions without a floor plan.
Electrical redundancy will not be a problem because the hospital has back-up generators. Energy, Bill Wann, Steve Weast, myself and others can give you advice on larger tanks but I would highly recommend that you get to see some of them in person. This is the only way to build your confidence for a project like this.
Look for large tanks near you including any public aquariums and get in-depth tours. There will be much to study including flow, redundancy, lighting, control, wet room accomodations, filtration etc. and this could be a great opportunity for you to expand your knowledge and contract out to others.
BTW, unless the tank is sitting on the floor, the kids will not get to enjoy the upper half of it. I too would recommend a longer shorter tank. For a system that size you need quite a bit of space for a sump, RO/DI and SW storage, and provisions. For instance, when buying salt for that size tank, you will be getting 20 buckets/boxes to a pallet at a time and you need a safe place to store it.
It's a big job but I set mine up while recovering from a stroke, so you have a clear advantage!