CachyOS KDE on ASUS VivoBook with MX130 – font scaling, NVIDIA issues, partitions, and distro advice

[JekaSylar]

Hello, please advise what I should do.

My laptop:
ASUS VivoBook 15 X510UF-BQ001
Intel Core i5-8250U (4 cores, 1.6–3.4 GHz)
NVIDIA GeForce MX130
16 GB RAM
1 TB SATA SSD

I have been using CachyOS KDE for about 3 months. In general I like it, but I have several problems and questions.

1. Small fonts in applications
   Even if I set font size to 14, some apps still look too small and I have to scale them manually.
   Viber looks especially bad.

2. Problem with GeForce MX130
   Hibernation does not work correctly.
   Sometimes the laptop does not wake from sleep, I get a black screen with numbers and an NVIDIA error.

3. Security question
   How safe is CachyOS?
   Some people say Fedora is more secure.
   Others say clean Arch Linux is better.
   I tried Arch, but it requires too much manual setup (snapshots, configuration, etc.).
   CachyOS is easy because it works out of the box.

4. Disk partitioning question
   I made 200 GB for / (like Windows C:), but after installing many programs only ~35% is used.
   Swap = 16 GB.
   What is the correct partition layout for Linux?

5. GPU question
   I am thinking about disabling the GeForce MX130.
   Drivers install automatically, but I don’t play games on this laptop.
   I only use it for internet, movies, and photo storage.
   Would it be better to use only Intel graphics for stability and battery life?
   How can I disable the NVIDIA GPU on a laptop?

6. I tried Windows 11 again
   Yesterday I installed Windows 11 and the laptop became very slow, noisy, and laggy.
   So I want to return to Linux again.
   I have another PC with Windows 11 for work (.NET, Photoshop, etc.),
   so this laptop is only for daily use.

7. Desktop environment question
   What is better for my case:
   KDE, GNOME, or COSMIC?

I would appreciate any advice.
Thank you.