I like your suggestions. However I went a completely different direction and switched the Black out for Red. This way I have shatter and two creatures that destroy whatever I turn to an artifact every time they enter play (Mimic Vat).
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That or Vampire Hexmage + Dark Depths = 20/20 flying nasty for about 2 black mana.
I would maybe replace Twincast with Jayce's Erasure since you have the leyline and Hivemind. Just one Erasure doesn't do a lot but 2 or 3 or 4 is a nice free (once they are out) way to mill.
I don't know that Coat of Arms works that well here. Do the tokens generated by Kher Keep have the type Kobold? It doesn't say they do.
Any suggestions on the side board would be welcome, seeing as how it is a second and unexpected tutor pool it seems like a good place to handle special cases.
I'm not positive about the land balance. The fixers can really slow it down if they are all I draw at the start but that shouldn't be super common. Once other land is on the field the fixers also produce color so I think they will work. Any suggestions?
Punish Ignorance is too slow in my opinion, especially if you are worried about early game. If your big concern is early game I would go with straight counterspells or something like manaleak (they probably won't have 3 extra early). Counterspell would be useful all the time though.
Interesting deck, I think it might be a bit vulnerable to a good fast aggro deck especially with the potential for a lot of lands not producing until the second turn they are out.
With all the land untap and return to hand you have in there, you might want to work in a few Winter Orbs. It would also have the benefit of targeting the tangle wire more at creatures as lands will likely be tapped.
I would probably replace Joraga with Rofellos Llanowar Emissary he should be a faster means to the same end (lots of mana), you can only have one out but he gives a lot of mana and you only have to tap one creature. I would probably side board some Dense Foliage and Gaea's Touch too. It looks like this might be a little slow in the early game which green really shouldn't be. It would be interesting to play this with my mono-green: http://www.mtgvault.com/ViewDeck.aspx?DeckID=87144