I have started my own business but a slightly different scenario…I have partners. If you’re looking to join your father and then take over the business after a few years, that’s one thing. But if your father is leaving as you come in, that is another. I have trouble believing that he will hand it over, lock stock and barrel w/o working you through the business acumen parts of it.
Your father is, effectively, your business partner. My biggest recommendation to you is to most definitely NOT make any decisions or formulate any plans like your considering in isolation.
Your father has invested a huge amount of time and passion into this business and it is awefully disrespectful to think you can/should come in and change it w/o consulting with him on it. You may find, that he would rather sell the company and provide you with proceeds to start your own business rather than change what he’s built.
Businesses are very personal, as you’re already finding out by examining what you think you want to do with it.
Talk to him. Learn from him how you can build that business acumen to develop, foster and grow those channels into the type of business that keep you fulfilled.