Is the backlot tour separate from the Theme Park? Admission price? Or is it all one park for one admission price? We would like to do just the studio tour - is that possible?

Unfortunately you have to pay to go into the Universal Studios site to be able to go on the tour of the back lot.To do the studio tour I think you will have to book the VIP tour (which is worth every penny!). The back lot ride takes you around the back lots but not inside any of the sound stages. Have you considered doing the Warner Bros. Studio Tour instead? It is a great tour that takes you through the back lots and you get to visit sound stages (for instance, where the Ellen DeGeneres show is filmed). Could be worth a thought and it's not really expensive.

You have to buy a general admission ticket to go on the studio tour.

It's all one price of admission. Have fun!