Hello! I'm on mobile and bad at organizing my thoughts, but I thought I'd attempt to tackle some of this.
You can experiment with different types of models and bring them into Cura to see what the results will be yourself, but typically your focus should be on creating "water tight" meshes, where the normals of all polygons face outwardly from the mesh and there are no deleted faces or holes between them.
Individual polygons don't have any thickness on their own, so if you delete faces on a primitive cylinder and bring it into Cura, when slicing it will attempt to "close" the hole left behind in order to make the mesh water-tight.
So, say you wanted to make a cup. You generate a cylinder in Blender of the right size, then delete the faces on one of the caps to create a cup-like shape. When you bring this object into Cura, it will not be able to see the back faces of the polygons inside of the cup, because it's reading the normals on the outside of the cup for those polygons. They can't serve as both the inside and outside, and they have no thickness. So, Cura will try to close the hole at the top of the geometry, basically just giving you the cylinder you started with.
You could fix this by just extruding all of the geometry from your cup version of the cylinder, which will create a perimeter of faces on the top edge, and will leave you with inside and outside polygons. That is what Cura will read to create your shell.
On that note, printed models are made up of effectively two components: shell and infill. The Shell is made up of the outermost layers, which are the strongest. The infill is a pattern that supports the interior of meshes. If you printed a sphere, you likely wouldn't want it to be made of 100% solid plastic because it would be a waste of materials and time. So infill supports the shell with a pattern, kind of like a honeycomb, that is just meant to make sure the inside isn't empty but is strong enough to withstand some force. On average, this is usually only about 15 to 30% density.
There are many great articles and YouTube videos out there about the process, and I'm sorry that I don't have anything to point you towards right now. If you have any questions about anything, I'd be happy try to help as best I can.
From a cis male's perspective, I think you pass well! Both on initial impression and even critically.