You aren't crazy. That sounds like something I would SO do!
First tip: If you are getting a Park Hopper at WDW and have any leftover days on your pass when you leave, you can use it at DL. Yes, really.
Second: You said you are arriving at LAX on Thursday night. Do not drive from LA to DL between 5pm and 7pm. You will just get frustrated with rush hour traffic. Eat some dinner and then drive. You will get there much faster and be happier when you arrive.
My DH and I took a trip to WDW for our 10 year wedding anniversary in October. We planned for 2 months and researched and read and... and... and.... Don't worry about all that for DL. You are going for a day. Just go to get a taste for it and enjoy the Park.
Unlike WDW, DLR's 2 parks (DL and Disney's CA Adventure) are right across from each other and very easy to walk back and forth in between. Most of the things on my "do not miss" list for DCA are at WDW (Toy Story Mania, Soarin', Muppets, Crush). I would take some time to check out the Animation Academy. If the animated movie making process interests you, it's wonderful.
Fireworks and Fantasmic!:
There are no fireworks at DL right now because Main Street is having work done to it. So, you don't need to worry about that. Fantasmic! is every night, however. It is arguable whether WDW or DL has a better Fantasmic!, but they are both shown in a very different place. WDW is in an arena, DL is out in the open along the river. It would be fun (I think) to compare the 2 so close together. People "camp out" for a good spot for Fantasmic! at DL prior to the show. You will have to decide if you want to spend your time doing so. If you are going alone, you can probably score a decent spot about 20 minutes before showtime if you are very nice to CMs and fellow guests.
Not sure what you like and what interests you so no clue what else to tell you about. Hope some of this helps. If you have questions... post away.
Have a great trip,
Dreams
P.S. The previous poster mentioned the Sunwheel. It is closed for refurbishment, so don't worry about it. Also, in addition to hawky7's list, here are more attractions that are only at DL, not WDW: Alice in Wonderland, Casey Jr. Circus Train, Main Street Cinema, Mr. Toad's Wild Ride, and Storybookland Canal Boats. Also, if you like Castles and Sleeping Beauty, Sleeping Beauty's Walkthrough is not to be missed. Nothing exists like it at WDW. Lastly, I will say that most people will agree without question that Pirates of the Caribbean is better at DL. Be sure to ride it.