Congratulations on your new business. While you may use your personal PayPal account, the better course of action would be to setup a separate PayPal account to keep track of your business activity. This will provide for better accountability. It is always advisable to keep business and personal activity separate.
Depending on how much you make at your business, as you suggested, you may want to make pay quarterly estimates. In addition to your normal federal income tax, you will have to pay self-employment tax (15.3%) of your net profit.
As for your MN business license, you need to go to https://mn.gov/deed/business/starting-business/legal-regulatory/ for information on licensing.
A helpful link dealing with other questions that may come up regarding your new business, a good place to look is: Starting a Business? (How to Start a Business Guide) (https://blog.turbotax.intuit.com/self-employed...