Im a beginner hobbyist and want to eventually make my own portraits and character art. How good at traditional drawing do i have to be to make things of this quality? How good at 2d must one be to make quality texture maps?
>How good at 2d must one be to make quality texture maps?
Pretty good. But it's not just about the 2D texture quality. To make materials like the ones you see in 'fine-arts' renders like your pic related you need to become a good shader composer and have a firm grasp of the tech you're using.
For making artwork it is enough that you know the materials of your software very well.
You know what happens when you crank any dial and can get the surface to shade as you like it.
Once you are very good at doing so you will realize there are really cool things you could do, but the software lacks nodes or dials
for allowing you to make it happen, so there is much merit in becoming a tech-artist yourself if you advance far enough in this art.
Actually programming shaders is def not required tho.
Still, studying the technical side of things a bit will give you a grasp of how things work and will demystify settings for you.
>To make my own character's do you think I would need more than to be good at basic sketching?
If you're already good at basic sketching you have all the requirements to do well in modelling and sculpting.
But making characters is a deep topic, especially if you have animation in mind.
Expect it to be at least a 10 years endeavor to become anything like hollywood-tier good at it if you're just starting out.