ZBrush can do things that animation packages cannot specifically because it is NOT an animation package. Its design allows it to focus your system resources in totally different ways from what an animation package does, in turn allowing you to sculpt in real-time with models of up to 100 million polygons (or even up to 1 billion polygons if you use HD sculpting). These differences in what is happening behind the scenes in turn require differences in how the software is actually used.
For example, an animation package gives you an infinite space. You place your objects in that space and move your camera through it in order to see your objects from different angles. ZBrush on the other hand is a window into a finite space. That window is stationary. Your objects are placed in front of that window and move in front of the camera. This is a subtle difference from the user perspective but a significant difference from a workflow and UI perspective. You are fighting with ZBrush because you’re trying to make it behave like an animation package when in fact it’s more like a paint program – one that just happens to be amazingly good at sculpting.
You came to ZBrush because you heard it can do things that other programs can’t. Don’t get mad at it when those differences demand that it behave differently from those other programs as well.
You would do yourself a HUGE favor by reading the introductory documentation. There is a Getting Started section that explains the most essential things to understand as you start to learn ZBrush. See Basic Concepts.
Shortcuts: Anywhere a shortcut says Ctrl, on macOS you use Command instead. See http://docs.pixologic.com/getting-started/macosx-windows-versions/
Your first picture is explained in those basic concepts. See ZTools and Edit Mode. The shortcut to clear the canvas is Ctrl+N, so on macOS you would use Command+N. This removes everything that is not currently in Edit mode.
For the second picture, you’re pressing keys and clicking buttons at random. Strange things are going to happen.
In the third picture, the window you want to remove and complain that you can’t get rid of actually tells you how to get rid of it. If you have Cinema 4D installed, click the button to Browse for it. If you don’t have it, click the “Not installed!” button. Windows don’t have text for no reason. Please read that text.
With the fourth picture, you’ve been using Canvas Zoom instead of Object Zoom. In other words, you’ve been doing the same thing as zooming out in Photoshop.
I don’t understand your description in the fifth picture. But I can tell you that the ZBrush UI is contextual. It disables features that can’t be used with your current selection and in some cases removes those features entirely. In your screen shot you have the Simple Brush selected. This is a 2.5D paint tool. Since it is not a 3D object, any buttons that only operate on 3D objects are grayed out. And since it is the Simple brush, none of the Tool palette’s sub-palettes contain any features that work with it so ZBrush removes those sub-palettes entirely.
The sixth picture is the same as the first. You’re using your Tool as a paint brush instead of going into Edit mode so that you can sculpt it. Meats Meier made his name by capitalizing on this. But he also took the time to read the documentation and understand the basics first.
When you draw an object that you want to do this with, press T to enter Edit mode. You can now use the Tool >> SubTool palette to add more objects, split parts, etc. Tool >> Geometry to subdivide, use DynaMesh, etc. And so on.
T (for Transform) is the shortcut key to switch between 3D editing and 2.5D painting. When in not in Edit mode, everything in the Tool palette is a paint brush that adds pixols to the canvas. When in Edit mode, you are locked to that specific Tool but can add SubTools and create really incredible models. That is also when you can use the Brush palette to switch between mesh editing brushes.
Again, it comes down to spending some time reading the documentation. You have been quite literally the guy who gets into an airplane and complains that it doesn’t drive like a car. 
And on top of that, you’ve been sitting in the cockpit pushing every button you see without having first read the flight manual.
In addition to the Getting Started part of the documentation, you should spend some time with the Getting Started tutorial videos. Especially the ZBrush Introduction series on that page, the ZBrush UI section and How to Start in ZBrush.
And on top of that, you’ve been sitting in the cockpit pushing every button you see without having first read the flight manual.
