Yes, I have builds I have customized to my liking, and removed all the unnecessary (to me) pre installed addons that I will never use anyways. Lots of tweaking to get them how I like (simple/clean/peppy). I keep 18.9 with my modded build just in case 19 screws up enough for me to jump ship til it’s more stable. Been close a few times but got the issues sorted in the build to alleviate the glitches, well 99.9% of them.
Not sure why people making builds install so many useless addons and leave them there before releasing the build, probably one of my biggest issues with every build I have tried, and believe me I have tried a LOT of them.
Solid Questions #1 - Definitely No, it will create issues. #2 Gamer yes but only if used extensively mainly for games, Streamer No #3 No, far far better is to use an App named Background Apps & Processes List
There are a lot of Nvidia shield setup videos on YouTube that are very good from people that know what they are doing as far as going into developers options. How To Setup The 2019 Nvidia Shield Pro Step By Step (March 2020 Edition) - YouTube. This guy Lee has helped me out a lot with set up of my sheild he starts from the beginning setup is easy wort a watch. Hope this helps