This is our first
Disney cruise in February as well, we plan on doing 7 nights in WDW before the cruise, we plan on doing at least 5 days of the parks for a few different reasons, we can never decide which parks to skip if we do less than 4 days (and to us the hoppers just are not worth the extra money, we rather just spend a full day in each park), after the 5th day the price per day drops dramatically per day, so we like to have the option to hop in the park or something for like $20 if we can not find something else to do, but you would have to add the days before you use the last day (If on day 6 you decide to go to MK but you have no passes left you would have to pay full price. If you want to add days to get the discount it has to be before you use all that passes, and the best discount is after day 5.)
We are not AP holders so do not know much about it, we have thought many times to do it but then always worry if we do not use it enough or get a chance to go back again within the year.
As for Universal I myself would skip it. I am not a fan, the prices are more than Disney and the only good rides are Harry Potter but have to pay for both parks to even enjoy the full experience. I think it is something to try absolutely if you have never seen the wizarding world of Harry potter (that is literally all US/IOA has going for it in my opinion. I would rather spend my time in the happiest place on earth, even if its resort hopping or a day in Disney springs, hands down better than spending it at US/IOA.
Budgeting is really different for everyone, for us we have no children, my husband and I both work full time jobs, and we can live comfortably on one income so when budgeting for vacations or other expenses my husband will pay for everything and my entire check will just go into our savings account. If you can not do an entire paycheck, just do what you can afford without cutting yourself short. If you get your nails done regularly cut that expense for a few months and put the money you would spend on your nails into the savings and bam in 3 months you will have $450 saved. Sounds like you have a lot of cost already taken care of with the ability to stay with your friends.
If your friends are in Orlando I would stay with them and leave for the port the early morning of the cruise, it would cut the cost of having to get a hotel for the night, plus I am not a fan of moving place to place, the less I have to move around the better. We love road trips so the four hour drive would not bother us one bit.
Whatever you guys decide to do it will be magical and you will have a wonderful time!