That's a LOT of questions
WELCOME to the forum.
First off... Age isn't a factor because just about anyone "can" fly a drone.
From my point of view and ONLY my point of view..
Steps:
1) Have an eye for composition and be a good photographer. Owning/Flying a drone does not a Photographer Make.... The drone is just a 3D tripod for your camera and if you aren't able to take good pictures without a drone then you'll take the same "caliber" of pictures with a drone just from a higher vantage point.
2) Become a good photo/video editor (whichever or both depending on what services you offer). If you can take the images you produce and "tweak" them in Post Processing you'll help differentiate yourself from the "right out of the camera gang".
3) Become a really good marketer in order to sell your services. You'll wear many different hats as a Small Business Owner and you need to be able to talk, sell, and close the deals with comfort.
4) Be really good at some specific services as "Drone Photographer" in itself doesn't really do much for a career.
5) Get a quality sUAS (drone) and become very proficient at flying it in a controlled, safe, and intentional manner.
6) Do the research for your local area and develop a detailed and comprehensive Business Plan. I'm not talking about the 1-2 page template you get from the internet. Spend the time to build your BP and get it right. Doing so will teach you about your business, your competition, your local market, your marketing strategy, and even help you define your pricing scheme. We took about 6 months to develop ours and it literally changed how we structured our company as we learned more about our competition and local markets.
7) Don't go out and go deep in debt buying the best of the best from the start. Invest slow and build your business. No need to have that flashy new car that your business can't afford to begin with. We started our company from a small savings/stash and have not borrowed any $$ to date. As the business grows and your needs grow then buy the better and newer equipment. We were still flying old technology for a few years after the latest and greatest came out. Some people said, "You can't run a REAL drone business unless you have this XYZ drone." Well I just kept doing what I was doing and taking all those checks to the bang while still flying the 3 year old technology. The clients don't know which drone I'm flying they just want high quality product for a fair price in a timely manner.
Good luck and SAFE FLIGHTS!
Allen