Any one of those questions deserves a 1000 word answer, and a real plan.
For music production, there are schools all over the country that teach this. You can also attempt to learn by watching free or low-cost videos online, but what you usually miss is picking up stuff from observing peers and getting feedback from pros. If you are starting from scratch expect to spend a few years getting minimally competent, and at least a decade before you can do it professionally.
There is no true shortcut to finding a fan base. You need to play, play, play in lots of different situations, as you cannot know where your fans are hiding out until you and they cross paths. After that you have to regularly communicate/market to them or they will be your ex-fan base real soon.
There is a whole sub-industry built around song pitching and licensing. TAXI is the best known organization, but there may be others. Be aware that unless your songwriting chops are EXCELLENT, you will be wasting your time as the competition and quality level is fierce. If your songwriting is not ready yet, you need to spend significant time (and probably money) to get it there.
My feeling is that each one of these could take many years. If you are wanting to do all three then that is a serious time (and money) commitment as well as an organizational challenge. Are you ready?
