Please submit an issue explaining your proposed changes. It is not guaranteed that your changes will be implemented, but it will be properly considered.
The most intensive parts of the modpack are the shaders and Distant Horizons which can be reconfigured or disabled in their respective options menus. The only other potentially resource-intensive mod is Terralith which can be disabled on the world generation menu.
You can do this by preserving your options.txt found in your modded instance directory and replace it when you migrate between modpack versions. However, keep in mind that you may need to reconfigure your key binds when new mods are added.
Most configurable mods in this mod pack will support Mod Menu, which can be accessed in the game's pause menu. Other mods may require manual configuration. Information on any mod can be found on its respective mod page.
This modpack was configured in a very careful and deliberate manner to deliver a stable and consistent gameplay experience. No guarantees can be provided about stability, balance, performance, or gameplay if the modpack is modified in any way.
No. I'm not going to support Overwolf and you shouldn't either. It is an objectively worse platform than Modrinth and I don't care enough to go through the pain of supporting it.
Yes, it should be fine for the most part. However, it is still highly advisable that you create a backup of your world before attempting to do so.