Yeah, just make sure you read up on the study material and understand it all well enough. I believe they hold interviews during the weekends and the wait times vary throughout the weekend but for me I had to wait about 3 or 4 hours before getting an interview.
OPS is pretty easy to get into. The wait times for interviews can be long, but much much better than RED. The actual interview is pretty easy too imo. Just make sure to read through the interview prep.
This would depend on the distro you use. Most distros will require you to enable a non-free repository before you can install anything that isn't Foss or open source from the official repos. You could also use an FSF approved distro. Keep in mind, the FSF will only approve distros that don't include any non-free anything in the official repos. Besides that, you just have to know the licensing before you install it.
Maybe a little late to reply but I use steamtinkerlaunch. You can set it as a compatibility tool and it'll open a menu whenever you use it that'll have an option to install/open Mod Organizer 2. Manually modding does work but I can't remember exactly how I used to do it since it was a few years ago and I'm sure things have changed since.
Generally I've found the people who say this get privacy and secrecy confused. You close the door when you go to the bathroom because you want privacy, not because you have anything to hide. Everyone has a pretty good idea what you're doing in there but you close the door anyways. Secrecy would be if you were cooking Meth in the bathroom and wanted to keep it a secret.
Low bar