1) Install GE if you need stuff like Shadowplay and Ansel otherwise don't bother with that bloatware.
2) Yeah, NVCP is lacking many stuffs unlike Radeon Settings but fanboys said it works so it just works.
3) Keep it.
4) Not sure about this one, my 980 Ti got 3 fans but it only show 1 fan in MSI AB. I know some cards like the old MSI Lightning or Sapphire Vapor-X the middle or smaller fan got it's own controller.
5) "Power" show how much power your card is consuming in percentage relative to BIOS power limit. If you want to check the exact wattage it currently using you need to use HWiNFO alongside MSI AB.
6) Afterburner show "effective memory clock" for Nvidia cards. For GDDR6/GDDR5X like 2080 you need to multiply the base clock speed with 8 while GDDR5 you need to multiply it by 4. A GDDR5 RX 580 with 2000mhz memory clock is effectively run at 8000mhz. HBM clock speed is slower but it got HUGE memory bus width. 256bit in 2080 vs 4096bit in Radeon VII.