You're from Central IL - my question to you is this - have you ever driven in morning or evening ruch hour in Chicago? If so, you have the mettle and wearwithall to do our LA traffic.
I used to commute up to work in Chicago (from LA) and I can definitely compare the two!
The biggest thing you want to remember is to avoid the major rush hours and just wait it out if you miss the window. If you are done at 5 - have dinner where you are and wait until 7 to go back.
You can definitely do all 3 of those things in one day. You just have to plan it out.
The Disney Concert hall is in the heart of downtown - off the 101 and 110 freeways. The 101 then can take you into Hollywood - get off at the Hollywood Bowl exit at Highland and go 3-4 blocks to Hollywood Blvd. Soda Fountain, Kodak Theater (where the Oscars are held), Hollywood Walk of Fame (Stars in the sidewalk) and the Mann's Chines theater (the DHS icon with the footprints) are all on the same block. You can park under the Hollywood and highland complex and get a validation if you stop in one of their shops - easy to do, since there is food and a BeardPapas creme puff shop (a must try - located on the first level)!
You can then take Highland straight south to Wilshire and drive straight to Rodeo Drive - maybe 20-35 minutes based on traffic. Doing this drive will take you past the LaBrea Tar Pits The LA County Museum of Art (LACMA) and the Peterson Auto Museum (with a classic car suspended over the entrance).
Universal is also a straight shot up the 5 to the 101 (4 miles from my house). Not a bad drive, either. The Hollywood and Highland area is just on the other side of the hill from Universal, so you could even combine those two activities. There is easy traffic between the two.