How are you playing your deck? Casually with friends? Planning on going to events at the local game shop? Do you plan to keep the deck in a standard format (see link below)? That can change people's advice a lot.
I honestly doubt I'll play any tournaments with this deck (or any really.) I mainly got into this for the purpose of playing with friends. So I'll probably keep it VINTAGE or MODERN.
Do tournaments tend to stay STANDARD?
In general there's nothing "wrong" with your strategy. You need to shore it up some and get a more focused strategy, by obtaining more copies of important cards.
The biggest thing I'm wondering is if there is just no way around having duplicates in a deck. I'm not necessarily against it, though I do like the variety of different cards. I'm assuming their must be a way to capitalize on both, in that there must be such a variety that different cards can do similar things to others. I've already noticed some crossover. Perhaps this is an absurd question.
And, elpablo, thank you for all the resources. It's nice to have the stuff I need to know streamlined for me. I really appreciate it.
It's a little overwhelming with the massive amount of cards and ways to play, but certainly keeps it interesting.