Only do Toy Story and Splash Mountain with a fastpass...there are some long lines in the park (Radiator Springs, Space Mountain, etc) but none are as interminable as those two.
Splash Single Rider is usually pretty good....... and you'll often be able to go on together. That's what happened with my husband and me. I think the regular wait was 60 minutes or something around there and we only waited 15-20. Single Rider is often very good, but if the CMs tell you Single Rider is backed up, listen to them. They ain't lying. We ran into that with Indiana Jones. Didn't want to believe the CM and ended up waiting longer than standby. Standby was only 25 and I think we waited around 40, the longest wait of our trip. No fucking cell or wifi service in that line either!
Get the Monte Cristo at Blue Bayou or Cafe Orleans. It's fucking amazing. Get the Fried Chicken at Plaza. It's fucking amazing. I'd say most food is overrated at theme parks but those two actually lived up to the hype. Also try the beignets at Ralph Brennan's (they have a counter service area so you don't have to do a sit down meal) for some good shit (or at least it was for me, having never been to New Orleans).
Chef's Table at Napa Rose kind of sucks. They mostly gave us shit from the regular menu except we couldn't pick what we wanted. If you do Napa Rose, just do the regular menu. The food is great and the place is romantic; nice place for a couple.
Get Maxpass on the DL app for $15/day per person. Includes FREE PhotoPass (which is worth more than $15/day by itself) and it makes it muuuuuuuuuch easier to get Fastpasses (basically allows you to book FPs via your phone....... often with earlier times than paper because cancelled ones go back into the MaxPass queue, but not the paper queue).
Definitely stay offsite. The prices at the DL onsite hotels are absurd and not worth it when there are many hotels literally across the street- some of them even closer than the onsite hotels- for a fraction of the cost.
Take your time and definitely try out some smaller rides and attractions. These often have short waits, so you have little to lose. One of our favorite rides at DL is actually Snow White's Scary Adventures, a dinky old ass ride. But my husband and I both LOVED it. It was our second favorite after Space Mountain.