I can't make sense of all your options
so I won't try and make you a plan, but here are some suggestions: I hope they help, rather than confuse the issue.
I would suggest that Epcot is good for 2 (or more) half days - it opens till quite late at night, much later than the other parks, so I would suggest getting there around 2 or 3 depending on your nap schedule and staying all evening- this works well for us.
Also Future World tends to be very quiet in the afternoons - I think most people get there early and then move into world showcase after lunch.
MK I would plan a couple of trips too - if you wake up early, then get there before opening and spend the morning there - leaving for your nap just when it starts to get really really hectic.
I'm not so sure about MGM - I think Fantasmic is usually on about 8, and if you want to see it, you need to either do a dinner package, or get to the stadium at least 1 1/2 hours early. Which means if you got to the park later on, you wouldn't get much time there.
I would visit everywhere, but plan on revisiting MK a few times - I think 3 short visits is better than one long day. We do the same with Epcot as we really enjoy it, it's more fun each time you go back because you can revist your favorite things and also find new things that you missed the first time.
It looks like you have 6 days in WDW - I would probably skip Universal unless you are really keen to go there - I would take more time at WDW, so you can relax and enjoy it, rather than feeling rushed that this is your only chance to do something.
I presume you've got this info already, but just in case
the early entry days are
Sunday -----Magic Kingdom
Monday -----Disney's Animal Kingdom
Tuesday----- Disney's MGM Studios
Wednesday --Epcot
Thursday -----Magic Kingdom
Friday ---------Disney's Animal Kingdom
Saturday------- Disney's MGM Studios
this means that you can enter these parks an hour early, but it also means that they are likely to be very busy on those days. If you are up early, then you might like to go early and then move onto another park later on when it gets busy. Personally, we try and go to the park the following day - although MK on a Monday is usually very busy, as we discovered last June - it was so bad we left and went to Epcot.
Also, you can check the park hours and fireworks/parade schedules here
Disney Park Hours
Have a great trip!
Bev