What size skateboard deck should i get from ccs.com? Should i get it assembled?

Deck size generally doesn't depend on shoe size but 7.75 would be perfect for a first deck. When you skate for a while you start to get a feel for what size you like. For example I've been skating for 4 years and I'm adamant that 8.25 decks are my favorite. I recommend you stick with one size for a few months until you are comfortable with skating in general. You just need to make sure that after a few months you try different sizes out. Make sure your trucks are the same size as the deck. You probably should get it assembled for a first complete. Look up youtube videos to see how it's done just so you can have some knowledge though.