Oh boy! Go to work for a few hours & look at all the new Qs!
as far as feeding, I always feed heavily. Turn off all flow, use a turkey baster & feed every single polyp & mouth in your tank. that includes all your LPS too. Inleave the flow off for an hour or 2 & them leave the skimmer off for the night. No reason to "feed" my skimmer.
For fractions of a tsp: The Salifert spoons are 1/5 of 1/4 tsp, if that helps any, bbut I always just rouond to the nearest 1/4 tsp, for ease of dosing.
VC=lowered nitrate=increased clarity=healthy, more colorful corals.
IMO, I'd never go w/o a skimmer. If you don't have a skimmer or sump, dilute the VC in a cup of tank water & pour into flow.
I hope I covered everything...