I have a thread for you to read, especially this post!
I would definitely recommend getting park hoppers. It is just so easy to hop, and there will be multiple occasions over 4 days when you will want to and will be disappointed if you can’t.
That said, if you’re on a budget and are really questioning that extra cost, you can totally do 2 days at each park without hoppers and be happy. (The problem is you will probably only need 1.5 days at DCA and 2.5 at DL, hence why hoppers would be nice.)
As far as snacks, get a churro (people say they are better at DL - don’t know if it’s true, but they’re good) and beignets at the Mint Julep Bar. Also I recommend getting a Dole whip and eat it while watching the Tiki Room, which I don’t think you can do at WDW. I know those are boring recommendations for WDW vets, but they’re must do’s.
I can’t tell you what time to rope drop so I’ll let someone else answer that one.
Have a fabulous trip! Let us know it you have more questions.