One HUGE key to the No-IL glacial spike build (which I run) is having 3x Flash Freeze Azerite traits. Without those you won’t want to be running No-IL. In No-IL you pretty much want to stack Mastery above all else (run Mastery 3 corruptions on everything you can).
I personally really like No-IL because the massive GS crits are ridiculously satisfying and it does very good damage up to M+ 15 keys
To your specific questions:
- As long as you get FF traits use GS, I don’t bother with the others
- Don’t need to prioritize in No-IL - Mastery is king
- Cap it at 33% (Shatter cap for guaranteed crits on frozen targets, but again Mastery is what you want)
- Unsure on this build, but I don’t love 3x Frigid too much seems like a poor man’s version of a combustion fire mage - would recommend searching for other Azerite gear to head towards either the Orb Build or Flash Freeze