Complete and utter beginner...

[Psychotime]

*Are there some drawing exercises I could do regularly that would help me to improve quickly? Something like quick poses exercises, but maybe easier for a beginner like me.

It depends on what you're trying to improve in. There's no general exercise that will help you with all things, because each subset of drawing is a different knowledge and skill set on it's own.

What are you trying to do? It's good that you now know that drawing takes practice, but it always bugs me when I don't have any real idea of what the artist wants to DO.

How about next time you post some drawings made for fun. The kind of stuff you're learning the skills FOR. The stuff you like. The stuff you want to do. That'll help us understand your goals better. What kind of art do you want to make? And don't worry about being "good enough" or whatever to start drawing it.

Draw it now and do your best, because once you do, it'll be automatically clear to yourself and everyone else what you need to focus on and the exercises you should do, and that's the first real step to improving yourself. The general advice you've been getting at this point is just general advice. You will improve faster with laser-pointed guidance tailor made for an INDIVIDUAL. Show your individuality!

Once the goal becomes clear the journey becomes much easier to map out.

And along with those drawings name 5 artists that you really love and wish to be like, and give a sentence saying what you like about each one.

*Should I keep copying drawings from Loomis? I also want to study Fun with a Pencil for a little bit.

Copy is probably the wrong word. You should be STUDYING what you see, as in analyzing and really trying to understand and internalize what you're seeing and how to utilize it in your own work. Copying is just copying if you aren't learning anything from it. If you aren't using your brain when you draw, you won't learn. Never do anything mindlessly and expect to magically get anything out of it. That's like trying to learn archery without trying to aim. To be blunt, it's a half-assed effort that will yield next to nothing.

*Is drawing with a 4B pencil like I've been doing okay? I haven't sharpened it for days, but I actually like the bigger line it makes.

Nothing wrong with that. As long as it can make the marks you want.