You park at the hotel.
Then just leave your car. It is totally walkable to the parks from the hotels, takes us 6-7 minutes to walk from rp to IOA........or of course you can take the boat. Very nice way to do it.
The 3 big rides, Rip Ride Rockit, Hulk and Dragon Challenge, due to previous accidents you cannot take anything on these rides, except a lanyard with your EP in it. Anything loose like wallets, cameras, phones, coins will go in a locker. These lockers are free for while you're on the ride. They are easy to navigate and takes a few seconds.
Some rides do allow a fanny pack as long as it has a three prong clasp.
Where there are lockers, you put things like backpacks in.
Rides are very different at Universal and they don't want things flying off and hurting people as has happened in the past.
Maybe a good idea to read up on the stickies and threads about Universal since you have never been.......and go to the website
www.universalorlando.com
It's full of info about parks, rides and hotels.