Your day looks fine and very manageable. Just note that Jungle Cruise wait times will most likely be around 30 minutes, and the Magic Carpets can vary.
Yes, you can pick up FPs one at a time after you use your original 3. We just got back last night, and the rides available for FP later in the evening can look limited when at the kiosks (and the lines in Tomorrowland and Fantasyland were long. The one by Jungle Cruise has been consistently easier to use both last year and this year.)
When you book your 4th pass, you can book it for anything on the kiosk, and then use your app to change the time and/or ride itself. After it is booked on the kiosk it DOES show up on the
MDE app. This can save time at the kiosk! Also, we have found that there are more options presented to you via the app than at the actual kiosk.
I hope that makes sense!
Just to boost your confidence, here is what we did on our first MK day on 7/15, park opening time of 8:00:
rope drop
buzz lightyear (we were the first people on the ride)
space mountain
dumbo
barnstormer x3 (they let us stay on...we could have kept going)
Little Mermaid ride
breakfast at BOG
It's a Small World
Haunted Mansion standby
Haunted Mansion with FP
dream along with Mickey
picked up Sorcerers of the MK cards
dole whips
tiki room
FP for Splash
FP for Big Thunder
lunch at Columbia Harbour House
Lots of photos on Main Street on the way out of the park for midday break around 2ish.
Much shopping and general lollygagging also occurred that morning. We took it pretty slow and easy.
We did come back later for a few attractions and the Wishes Dessert Party.
I hope you have an awesome trip!!