Crease sharpens the edges when you use a smoothing algorithm like the subdivision surface modifier. The higher the crease value the sharper the edge.
As for hiding face and inset, that unfortunately just comes from banging your head on the keyboard going why am I having XYZ problem and then learning how to fix those problems. Also known as experience.
As for feeling overwhelmed, that is both a good thing and a bad thing. It’s good, because it means you’re dividing in and learning. The bad part is it also means you need to slowdown, and/or redo the lesson or even walk away for a few minutes. Which is hard to do when you’re excited and energized to learn. So, embrace it. Also remember there is a lot to learn and you got this. I like this saying by Wayne, I’m paraphrasing “failing means you’re learning” he says it better and so casually, but it has made a difference in how I approach learning Blender.
