It depends, if you want to use my art for absolute private projects then it is okay.
Whenever you have the intention to earn or start making money, you have to contact me to obtain a license.
For example you want to use some of my art in your YouTube videos (even if you have no partnership & monetazation with YouTube) then you are not allowed to use my media.
License is needed at all times.
Media is usually in 4k.
No, for each project you need a seperate license.
Yes, you need to credit me in the description or in the end credits.
You can pay with paypal or cryptocurrency.
Yes, I can create what you desire.