Public school spring break where I live is usually in April, far later than the rest of the world. I'm not sure if LAUSD or Anaheim school districts follow suit, but if they do then you won't have to worry about spring break.
John Wayne Airport is the best airport to land in IMO. You can take the 55 to I-5 north & ride it about 15mins to the park. However, you're coming from the south, so you'll need to navigate surface streets a tiny bit to find the entrances to M&F or Timon lots.
-- PMM