Ok guys, So here it goes.
My original plan---
My current 20 gal FOWLR, my ideal plan was to get two porc. puffers.
The current, suddenly changed plan---
I have noticed two fish at the lfs, in a tank down on the floor, pretty hidden. The poor two guys are the best of friends..and I just want to give them a good home, Also do not want them to get split up. And in July, they will have a wonderful home in my 220!! So.. These two fish I speak of are, Niger Trigger, and Picasso Trigger. Which--ironically, are two fish that I have always said I would have!
These would be my only two fish in the tank, and are very small, so I think they will be JUST fine until July.
So my MAIN question----

Will they wipe out my hermit population? I will post at the bottom of this, the articles I am reading, never do they mention hermits

Will either of the two wipe out my snails?

Does anyone here have either of these two?

Will either of them eat my coral banded shrimp?

Will they bother my Coco feather? or little baby feathers?
------------ How about my Atlantic Lettuce Slug??
Ok here are my current tankmates--
Coco Feather
11 Tiny Hermits
4 decent size snails
Coral Banded Shrimp, (Body about 2 inches)
Atlantic Lettuce Slug
Very very small blue/green Chromis, in which I will be taking to lfs.

Also-- Wow I have typed a lot!!! But here are the facts I am getting from most of the sites... in reference to both fish.
The Niger Triggerfish needs a varied diet of meaty foods including; squid, krill, clams, small fish and hard shelled shrimp to help wear down their ever growing teeth.
Wow, I need help guys!!