Local ordinances may dictate that you can't open your well, but in my area of Ohio, there is no issue. It is very common to have to "shock" wells in our area due to iron bacteria. basically it consists of pouring chlorine in the well, circulating from the house back to the well via a garden hose and outside spigot for half an hour. Running water through each outlet in the house, hot and cold, until you smell chlorine. Then pouring more chlorine in the well, and circulating for an extra 10 minutes. Close the well back up. Let it set for 24 hours. Run the outside spigot until you don't smell chlorine any more (up to six hours or more depending on well depth). Then flushing all of the spigots in the house. It is quicker to drain the hot water tank through the bottom hose connection (shut off the power) then refill. I have replaced my well pump twice myself, shocking the well each time to kill the bacteria that I introduce. The EPA used to provide instructions on how to shock your well. If you drill a new well, you need a licensed contractor and appropriate permits. Plus you are required to test your well to prove the bacteria has been killed. I had to have a new well dug. The contractor took care of permits, but I had to shock the well myself.

The pressure tank only allows you to run water, maintaining the setpoint pressure, without the pump having to turn on every time a faucet is opened. Typically you will get about one toilet flush worth of water out of the pressure tank if the power goes out. Not much storage.

I bought a generator in 1997 to run my well pump and sump pump if the power went out. It is fed to the main panel through a double pole disconnect switch. Look around the generators in your local Lowes or Home Depot. There should be switch boxes and info available on how to connect them. Your local power company should also have information on how to safely connect them. You don't want to backfeed a house without the appropriate switch. Without it you could backfeed the line and possibly electrocute a power company lineman trying to restore power. Those switches are not cheap, but this type of service is what they are made for.