Good questions!
I'm very frugal by nature so the alarm bells started ringing. Have you considered dropping your hire car at the local station and then starting a new booking once the cruise is over? This way, you'll save the cost of a week of hire charges while the car is just sitting there AND the cost of parking at the port. You can book it in advance and save. You can easily drop people and bags at Disney and then drop the car at the office and they'll shuttle you back. The shuttle drivers have a name for this: Disney Dads -- lol!
As far as formal clothing, some people dress up, some don't. I am an excellent packer (I did 6 weeks in Europe with a backpack containing two changes of clothing and didn't really need the second one) and hate to bring more than I need. I have one dress (bought off eBay, lol -- told you I was frugal) that works for formal night, semi-formal night and Palo. I just change the necklace or my hairstyle and I'm all set. No one's ever said to me -- you wore that dress 3 times this week!

That being said, I may break that rule this year as I've now got photos of me at Palo for the past 3 years, all wearing the same dress. I'm starting to look not frugal, but cheap.
Bear in mind that your suitcases will likely stow under the bed. If they nest, you can do that and save space. We just splurged on new luggage this year (after 15 years, the old had served us well AND I got a half price plus 30% off deal

) and I got 3 nesting pieces. We usually also have gym bags for extras; they also fit inside. If you really run out of room in your luggage, you can always get small Disney bags/rolling duffels in the gift shops -- they usually have some sort of special going where you can get the bag for $10 or $20 if you buy a certain amount of stuff in the shop.
As far as getting to the terminal early, it's good for your boarding ticket but you basically just sit there until noon when they start letting people in. We were always on the early side but last time we got there around 1, and boarded immediately. We liked that a lot better. The only good thing about getting there early is to meet up with other people we've met online before!
Vegemite, hmmm. It is an acquired taste. However, having lived in England, I can definitely vouch for it tasting a LOT better than Marmite!
Where else will you be going prior to the cruise? I know you Ozzies come over for very lengthy holidays; the distance pretty much makes it a must. We'll be in Orlando for a couple nights before -- we are COMPELLED do the new World of Harry Potter attraction at Universal Studios!
