This is my perspective, being another Aussie who's been to Orlando twice, I will state I am nowhere near the fountain of knowledge that Robb is
1. You don't say how big your family is, but if it's more than 3-4 my recommendation would be to not stay on Disney property cause the rooms are small and expensive for what you get. That said, the magic bands are great with the fast pass bookings & the memory maker if you pay for that. Driving around Orlando is a piece of cake, lots of freeways, getting from park to park takes very little time at all and car hire is cheap.
2. If you're at all interested in that kind of stuff Kennedy Space Center is awesome, a very easy hour drive from the parks area of Orlando. If you like Coasters go to Busch Garden in Tampa (another hour or so drive). Seaworld & Discovery Cove are great too. If you have one you might want to take the wife shopping on International drive to keep her happy. NBA will be in season so you might want to catch a Magic game. There's no shortage of things to do in Orlando my friend.
3. Can't help you here.
4. I've only flown Delta once, they were fine, can't help you much on this one.
5. Very, very easy, pretty much freeways the whole way. Just remember to have some shrapnel on hand for the tolls (which don't cost much).