2. If you are only going to DL, and you plan to arrive 1-2 hours after park opening, then any day of the week will be fine. If you plan to arrive at or before park opening then choose a day when EMH is at DCA and not DL. That means Sun/Mon/Wed/Fri.
3. Typical advice is to focus on things you cannot experience at WDW. Or are significantly better at DL. These would include (and I am not looking at the refurb list so check that!)
Not at WDW
Indiana Jones
Matterhorn
Finding Nemo Sub Voyage
Toontown
Much of Fantasyland including:
Alice in Wonderland
Mr Toad's Wild Ride
Significantly better at DL
POTC
Space Mtn
and maybe...
Tiki Room
Buzz Lightyear Astro Blasters
As for shows, Soundsational Parade is worth seeing. I would tend not to spend time on fireworks or Fantasmic on a day trip.
Does anyone know about how easy it would be to hop from DL to CA or grab lunch at Downtown Disney and get back into the park? We can't stand kids so will need some booze to deal for sure. haha
Jumping back and forth from park to park was quite easy we found. When in Downtown Disney, you can either walk back - doesn't take long or you can jump on the monorail to get back into Disneyland, it doesn't take long and gives you a great look over the park. Does not cost anything to ride the monorail.
As for not being able to stand kids.....good luck with that one, both parks are full of them....lol
I am local to WDW so that's what I am used to. You will be surprised how close everything is. My first time there was for 1 day in Septemeber. Since we only had the 1 day we did park hop and it was great. We got SO much done. I know it was a low crowd time, so not sure about April. I went back this January and had the same experience- stayed longer but still went to both parks everyday. If you change your mind to check out both parks California Adventure is great to grab a drink and I loved Carsland and California Screamin'. Definitely plan to arrive early.