I have had two homes with wells and both required very minimal maintenance. Here's some tips and answers to your questions:
* You need to have a pump specialist in your contacts just like a plumber or electrician. If a lot of houses in your area have wells, one should be easy to find. They can also handle your water softener system and give you advice on how high of quality system you need based on your well water quality.
* Neither of my houses had water storage tanks - just 25-gallon pressure tanks. These tanks have a bladder that gets compressed and maintains your plumbing at 40-60 psi just like a municipal system would be, and also provide a little bit of storage. A pressure switch turns your pump on and off as needed. Your pump specialist can also handle this. Don't use a standard plumber.
* Instead of advertising free water, consider charging a $20/month well service fee for the tenant's water.
* A well doesn't necessarily mean a high water table. My homes were in the mountains where many homes had Wells that were over 500 feet deep. If your state requires well permits, the permit will tell you how deep your well is and how deep the water table was at the time of drilling. If you do have basement water problems, they can be solved with a well-designed french drain.
* If you are having more problems with your well than what is typical for that area, you may need to get your well inspected to see if your well casing needs to be replaced. That is the slotted pipe inside your well that allows water to infiltrate from the ground into your well. If it is badly corroded you could be pumping rust out of your well or you could be letting more than just water through your well casing.