Hiya bhatcher n welcome to the party!!
K for your question on how to cast on in the middle of your work, you would keep the same piece of yarn unless the pattern calls for you to use a seperate ball. But I am guessing in this case that it's not. So..... taking the working yarn, work to the place where you need to cast on (co) and make a loop with your yarn that looks like a backwards cursive "e" and slip that onto your right needle do that again and you've got your two co's. If you come across a pattern that calls for more than two just repeat that process till you get the amount you need.
This method is called "backward loop" cast on and it's on this page with a video "here"
also known as single cast on. This is the usual cast on used within a work; for buttonholes and fingers and thumbs etc.