Hurler and Thunder Road are almost ALWAYS complete walk-ons.
Top Gun (Afterburn), if two trains are running, is only about a 5-10 minute wait tops.
NightHawk is mostly always the longest wait. The very minimum wait is around 15 minutes long, tops could be close to 2 hours.
The Carolina Cobra is a surprisingly short wait, even if the que line is full to the max. If it is full, the wait is only about half an hour maximum.
Taxi Jam (Hey Arnolds Taxi Chase or something like that) never has a wait.
Runaway Reptar has a max wait of about 15 minutes.
Scooby Doo (Fairly Odd coaster) is usually a walk on, otherwise you'll only have to wait about 5-10 minutes.
The Goldrusher is almost always a walk on as well, the max wait time less than 5 minutes.
Vortex, if two trains are running, only has a max wait time of about 10 minutes.
The Cyclone has a maximum wait time of 8-10 minutes.
The Ricochet can differ greatly every day. Sometimes it's a walk-on, other times it could be as much as a 40 minute wait.
I do believe these are all the roller coasters, if not, feel free to correct me.
Wednesday is a great day to go. I've had pretty good luck beating the crowds Thursday as well.
Food is very expensive, as is drink. If you drink a lot throughout the day, I suggest two things. If you like soda's, buy the big plastic cup (biggest one they have. It's only like 2 dollars to refill the entire cup. The cup itself costs 7 dollars I believe, so it really pays itself off. You can bring it to the park as much as you want to.). If you drink more water than soda, go to any of the drink stations and ask for a free cup of water. You can get as many cups as you want to, all for free. (beware though, they are usually pretty small!)
The skytower pretty much NEVER has a wait. It's air conditioned, and you get an amazing view of the park and surroundings.
Try to ride the coasters throughout the hottest part of the day, because more people will be in the water park.
I hope this helped, and if not, PM me your question.
Ride on!
-billcollins531