How can I understand drums (dynamics/theory) so I can transfer what I hear in my head over to midi?

I'm working on a massive album that might be called baroque metal. I have all of the parts in my head, including the drums. While I have a solid understanding of the theory and structure of other instruments, I have no idea how I would go about notating drums by hand in midi to get an organic sound that is like my favorite albums. Eventually I want to get a real drummer to play the beats I compose, but I want to do an accurate and professional job myself, first, especially in case I can't find a good enough drummer.

From what I've gathered, I could go about this by learning various drum beats from a website like free music. I could analyze the drums in guitar pro of my favorite songs. Then, I could learn things like velocity, ghost notes, and how to move drum beats slightly off the beat so that it doesn't sound mechanical. Still, it seems like learning all of the beats on something like free drum beats would be a massive undertaking, especially since I won't be using most of them. I also have no idea how drums work, the theory behind it, or even how velocity and other dynamics around drums should be notated properly.

Any ideas on how I should go about studying this? I want to get full mastery on this subject so I can notate the beats in my head with as much clarity, depth, and technicality as possible. I don't want it to sound cheap or robotic.

Cheers.