There are no hardline rules when it comes to the exact number of given creatures in a deck, so use 40 as a general guideline, not a hard and fast rule
A two mana lord which buffs all your creatures is a pretty standard rate, but Lord of Atlantis does much for you than that: he also gives everything islandwalk
Not high powered compared to other effects but when you are mostly about the scaling effects or raw numbers this is a commonly played card
With Volrath, the Shapestealer in play, the combo alternates between two forms
Since it's a 3-mana land destruction spell, could it be viable for land destruction depending on the environment
These are some of the neatest cards in the set, and I'm going to rank them from least to most relevant in EDH