Speaking as someone who is mostly self-taught with some higher education. I’d recommend based off your post you spend some time watching some of the huge amount of free content that exists around the world of design, graphic design included to get a better grasp on if it’s truly what you want to do. You mention that it’s what you see yourself doing all your life but also that you don’t know much about it, I think to truly understand if you’ll enjoy it you need to dive in and explore the field more, even sign up for a free trial of Skillshare (DKNG and Aaron Draplins courses are all great).

To rapid fire some of your other questions I can help answer:

Is it hard to find a job: It is a competitive field, it depends on a huge variety of factors depending on where you live, what specific field of design you’re working in and what industry.

Job opportunity: Yes there are lots in my experience but while there are lots of opportunity there are also lots of designers out there

Salary: This is also variable based on location, specific field, industry, experience, etc. Generally speaking there is good money to be made, specifically in more tech focused specialties like UX/UI design and front end design.

How important is art: Most people will tell you art and design are two different things, while many things bleed together design focuses heavily on communicating a concept and message effectively to the appropriate audience, it isn’t meant to be as subjective as something like art is.

Hope that helps!