First off, welcome to the board! As for setting your U1 and U2, there's no "one-size-fits-all" settings that we can give you. For shooting indoors w/o a flash, you don't need to use U1, you can simply use anything other than auto-mode and the flash will not be fired. U1 and U2 are really meant to house specific settings that you find yourself using often and instead of spending time adjusting them back and forth, you can simply dial to Ux and they'll all be ready to go.
But given that you're new to your camera, I would spend a good deal of time shooting things indoors that would simulate your daughters gymnastics meet so that when Sat rolls around you'll have ironed out all the issues that will surely crop up. Try starting with "P" mode inside your house with approximately the same-ish light that you would expect the gym will have and take photos of your daughter and see what they look like. Do this experiment tonight and then tomorrow we'll be here to answer your questions about shutter speed (ie - camera shake and minimum shutter speeds needed for your type of lens to produce sharp indoor photos), ISO requirements for given shutter speeds and white balance. And if we get far enough tomorrow we may even talk about noise reduction.
DSLR camera's are wonderful inventions but unlike point-n-shoots, they're designed so that the photographer can adjust and meddle with all aspects of the photograph. In a way we're all a bunch of control freaks and these cameras suit our needs rather well. On the other hand, if you're just starting out you may find the vast amount of optional changes you can make on a dSLR a little daunting. But with a little effort and a lot of quick learning you'll be ready by Sat.
