Do I have the legal rights to charge storage fees on vehicles left on my property?

There are specific rules about fees for storage and liens, etc., on vehicles. If you hold the property and charge fees, there is an implication that you are taking a bailment, making you responsible for their condition. This is probably not in your best interest. You would be better served having the vehicles towed away at the owner's, or estate's, expense. Before doing this, however, I would be sure to send written notice to the family or the administrator of the estate that they have a certain amount of time to get the vehicles before you have them towed. You probably should issue a written notice of abandonment and have it posted on the premises and mailed to the last known address, and any other addresses you have for the family, letting them know you will be disposing of the cars within 45 days per statute of they do not get them otherwise. It would be a good idea to review your situation in greater detail, however, with an attorney to be sure that a bailment hasn't already been created. If it has, you may have to take other steps to deal with the property.

Yes, you can charge storage. The amount must be "reasonable" under the law, so you might want to look at what it would cost elsewhere to store a car.

Notify the owner of the vehicle in WRITING that you are going to charge storage fees until the car is removed. charge $10 per day.

Yes, you can charge storage fees. You should consult a real estate attorney to review all of the documents and facts and advise you.