I guess I'm not understanding. When you are F2P there are only a few species that are playable. I became a subscriber, I thought more species would unlock but nope. I have read questions on here saying if you're playing a, let's say Twillek, and get it to lvl 50 that unlocks account wide. But how do you play the Twillek in the first place. Do I seriously have to pay 16 dollars a month as a subscriber and then on top of that pay either Cartel coins or 1.5 mil credits to unlock EACH race?

Only certain combinations are allowed, even for a real paying subscriber. You have to find a class that allows Twi'lek - the Internet says: Knight, Consular, Smuggler and Inquisitor.

 

So, look for one of those combinations. What I don't know is if a 7-day free subscription (no matter how you get it) counts for the above, so the other question is, "How did you become a subscriber?".

This site shows which species/class combinations are automatically unlocked for subscribers:

http://swtor.wikia.com/wiki/Species

 

And, after you play for a while, and learn the system, you'll find that 1.5M credits is pretty easy to come by anyway.