Hi There, to start with I can point you towards a forum that chats about Gold Coast theme parks
http://www.parkz.com.au/forums/ Everyone there will be happy to answer your questions.
Dont let everyone get you down about the theme parks on the Gold Coast. They really arent as bad as everyone makes out they just arent up to Disney/Universal level but no parks anywhere in the world are. The best way to treat the Gold Coast is like one big park in my opinion. Your best bet is to stay in Surfers Paradise as a base. Brisbane isnt very exciting for tourists and can be seen in a day. Visit Lone Pine Koala sanctuary while there.
Staying in Surfers will give you a good base to get around the Gold Coast. If your going to rent a car it would be a much faster way to get around that public transport. All the theme parks besides Seaworld are about 20 min drive from Surfers. You can get a 3 park pass for Seaworld MovieWorld and Wet N Wild for $100 that will get you into all of them. Movie world and seaworld are both half days parks and wet n wild can take up most the day if you want to. You also have dreamworld and white water world which are attached to each other an you can probably do both in a day if you want.
Surfers Paradise its self has alot to do with some great attractions like Infinity and Putt Putt and well as the beach. Just look up things to do you wont run out of things.
Anymore questions feel free to ask. I live in Surfers and am pretty good with whats going on around town.