I think this would benefit from a 1-drop mana dork. Noble Hierarch would be good, but good old Llanowar Elves or Elvish Mystic should work fine. Personally, when I go for ramp, I usually go the Arbor Elf+Utopia Sprawl/Fertile Ground route. I think 1-drop dorks are the best - they get the ramp going T1, when it really makes a difference. The higher the CMC, the less advantage ramp cards seem to make, at least in my experience.

Some cards that might fit: Savage Summoning, Thrummingbird, Savor the Moment, Gitaxian Probe

Sideboard ideas:Naturalize/Back to NaturePithing NeedlePlummet - not very good in most matchups but hilarious if you get to use it!Elixir of Immortality (against Mill)Dismember

I like the Naturalize of course for the deck, This deck is for some casual kitchen table multiplayer so it's not that competitive for one on one. You suggested a lot of good cards but if I can bring Voyaging Satyr online with a Nykthos, Shrine to Nyx in play I do alright. Or if I get a Karametra's Acolyte.