Hello. These are dmed's rules for elementary-age aquarium (take 'em or leave 'em, but they were learned at the school of hard knocks):
1. Whatever you buy, buy in multiples and specimens must NOT be distinguishable from one another. This prevents attachment to one "special" fish which can be heartbreaking if it passes on. When the kids want to name individual fish, tell them "they're all called (insert Latin name of species here)."
2. The only thing more traumatic for a child than a dead fish in the tank is half of a dead fish in the tank. For this reason, avoid barbs and other nippy fish.
3. Choose species that are readily available at any LFS and do not grow appreciably. It's easier to replace a 1" fish with a 1/2" fish than to replace a 4" fish with a 1" fish.
4. No fancy (fragile) species like fancy guppies or goldfish.
5. Absolutely NO pleco. Kids hate the idea of rehoming or "trading in."
I would choose two groups: one hardy species of "swimmers" and one group of either freshwater shrimp or corydoras.
Also, automatic feeders don't work particularly well. If you must use one, you definitely get what you pay for - don't go cheap. The ones that connect to an air pump work somewhat better, but if any moisture gets into the feeder, you will come back to a giant mess and possibly a huge ammonia spike. Most fish do not need to be fed every day.
You can start cycling the tank by adding an additional filter to your existing tank and let it run for a while, then you can move it to the new tank and immediately begin a fishless cycle which will go very fast with your innoculated filter.
My final concern for a tank in a church - how is the climate control in the building on days when there are no services?
