A general admission ticket includes all rides, but not food, parking, souvenirs, or other purchases. There's also a (substantial) additional fee for a VIP experience or for a front-of-the-line pass. But general admission includes all the regular rides and attractions.
It's sometimes possible to find discounted tickets online, though the discounts on single-day tickets aren't usually all that much. But if you're a AAA or Costco member, it's worth comparing prices (be careful to make sure the tickets can be used the day you want to use them), and you can search for discounted tickets online or check with your hotel.