Some say na mas mabagal yung pagccycle pag may skimmer. Pero marami pang argument dyan. Its up to you. Ako naka-on skimmer ko at least for the purpose of breaking it in.
Yung sa snails, personally I think di dapat lagyan especially pag may detectable ammonia and nitrite ka pa kasi harmful yan sa animals. They put snails to eat up the algae para hndi madumi tignan. Pero for me I plan to just let the algae bloom para mas marami maubos na nitrate. Pangit tignan but you're still cycling so what's the point of a clean looking tank? Better have the algae now than later pag may mga livestock ka na sa tank.
btw, yung apat na corals mo, pa-adopt mo muna. di mo mabubuhay yan kasi wala ka pang sufficient na ilaw. tsaka di mo magagawang favorable yang water quality nyang 5 gallons mo dahil kaka-set up pa lang nyan. wag tigas ulo.