1. Having two-ofs isn't necessarily a bad thing as long as you can draw what you need or get through your deck quickly. You have spells and creatures that take the mana straight from the deck so that in of itself is making your deck smaller. But if you feel as though you're having a difficult time with deciding what to keep look at your deck and ask, "what can I use consistently every turn in order to further the strategy of the deck"? This will help you decide which cards that you want to keep the most.
2. Well
aetherstream leopard has trample and it's a 3-drop so that's pretty good for a 2/3. Also as soon as it enters the field it gives you an energy which would fuel the
fabrication module (turning it into a 3/4 with trample for 3-mana). Also
fairgrounds trumpeter would be good in this deck because at the end of EACH end step it will get a +1/+1 counter if there was one placed on another card that turn.
Sage of Shaila's claim would be a great substitute for your
longtusk cub because you have no obligation to have to swing with it and it gives you 3 ENERGY just by
entering the field for only 2 MANA., scrounging boundar gives +1/+1 counters to which ever creature you choose.
Wily Bandar would be good addition to this deck because of it's indestructible factor. Also
wild wanderer can give you mana straight from the deck which in itself will thin out your deck for better card draws.
Larger than life would be a great 2 drop that will give your creature a huge boost for a low cost.
Nature's way will give your creature that extra trample you were looking for AND it serves as a kill spell that won't harm your own creature in the process like
prey upon. That's my advice on those two questions.