You can already do this, except for FP which isn’t on the filter because EHG doesn’t want it, and the formula.
The loot filter is actually quite easy to set up. You just have to start from hiding everything and then making rules for what you want to see.
You should look up tutorials on it, or check https://forum.lastepoch.com/t/1-1-heavyz-casual-loot-filters-for-all-classes-v4-1/25176.
This would be nice. But other than class specific affixes, you will be swimming in shards pretty fast.
I simply make a rule at the bottom that catches all the class affixes so I can shatter those. I never shatter anything besides those either.
It really is not. It’s actually quite intuitive. You should give it a try.
Maybe start with Heavy’s filter and then switch things up?
Although, as I said, it’s easier to just start your filter with hiding everything from common to exalts and then add rules for what you actually want to see.