A "quick and dirty" answer to the question follows. All can be entered from the command line interface:
cat /etc/os-release # provides NAMES, VERSIONS & some URLs for support
lsb_release -a # distribution-specific information; ref man lsb_release
hostnamectl # brief & useful incl hostname, OS ver, kernel ver; ref man hostnamectl
And as ...
I don't think you need to build a custom kernel at all. You need to build custom modules and load them in the stock kernel you already have.
Install kernel header files with sudo apt install raspberrypi-kernel-headers, and follow the instructions in the release documents to build the modules you need. This can be done directly on the Pi.
My advice is to use Buildroot (https://buildroot.org) to create your custom OS and/or cross compilation toolchain on your computer. You'll be able to choose which package to include in your OS with :
When you have successfully built your first os image, you can then customize the kernel with
Device drivers can be ...
There are some important issues I see so far. You are trying to do development in /usr/bin or in a subdirectory of it. I strongly recommend not to do it. /usr/bin is one of the most important directories of the operating system. It contains your programs, also important system programs and some may have special access rights. Doing development here with ...
You are using old deprecated settings for WiFi. I don't know where do you get this. With Raspberry Pi OS, WiFi is working out of the box. You only have to use the right settings. I suggest you start over again with a fresh flashed Raspberry Pi OS image of your choice. Then follow the official documentation for Wireless connectivity in the Raspberry Pi ...
Well, it took me a while to find the it, but the file I was looking for is called panel, located under ~/.config/lxpanel/LXDE-pi/panels. It also looks like this file should be treated with care as this file controls the taskbar as well as everything on it.
# lxpanel <profile> config file. Manually editing is not recommended.
# User preference dialog ...