Justina

Get the emed option. I believe they have a 3 for $99 option as well. The emed tests are simple and easy, literally takes less than 20 minutes start to finish with results and as long as you have wifi, you can do them at any time of the day or night, at home, in your hotel the night before or the morning of without worrying about making appointments or getting results on time. It's well worth the extra cost, which in the long run, isn't really that much more, for the flexibility, convenience and peace of mind they provide. 

I've seen a lot of posts about arriving early to check in.  Both on this this site and on social media sites.  It's like people are secretly hoping someone will tell them it's okay to arrive early.  It's not.
The arrival times are in place for a purpose and to ensure no one experiences a miserable start to their cruise vacation.  Standing around in the rain or the Florida heat and humidity for hours is not a great way to start a cruise vacation.   The security lines and check in lanes are not designed for everyone arriving in large masses.  When guests ignore their appointment times and arrive early it makes for a miserable experience for everyone including folks who hold the proper arrival time appointments who arrive on time.  
It's not okay to arrive early.  If you arrive early you are not just part of the problem, you are the problem.  

I saw a few strollers on my last sailing on Anthem last week.  Some were able to leave them in the hallway because of the configuration of the hall (there was more than standard hallways), same for the scooters, otherwise they might have to be in the cabin.  If you do get an upgrade to the ultra spacious cabin is it at the very front of the ship? If so you would probably want the stroller.....as the main dining room is at the aft (back) of the ship.  
does our cabin have the berth beds (pull down from the wall) or the sofa bed.  The pack and play would fit in the balcony f you did not have to open the sofa.

WOrdell1 mentioned getting another cabin.  I know when I tried to move someone inside of final payment my TA told me it could not be done.  I would recommend you speak with a TA (or with Royal direct if you are not using a TA) to explore that option further if you wanted to.  Ideal would  be connecting staterooms, where you can leave the interior cabin door open,

As for meals, your reservations should be linked and you should all have the same dining time (if you all requested the same dining time).  One of you can go to the Main Dining Room upon boarding, have all cabin #'s/last names available and confirm with the dining room staff that you are all booked together. It does not matter if you end up in a suite or not, you can all dine together.

Overwater cabana with a baby, crawling baby?  I think you wouldn't necessarily be able to relax as there are no sides to the cabana that I recall.  I know I have packed my own Tommy Bahama tent for the beach, it packs pretty small and is relatively easy to set up.  It has it's own floor, and sides, great shade and keeps the little one out of the sand for the most part (I have used it for ME to stay out of the sun!)
I cannot address the infant bottles as I did not cruise when my kids were infant age.  When I had my kids they were used to room temp water mixed with formula so there was no heating of the water so whenever I took them somewhere it was easy enough.
For the 11 year old-I have a pool float I LOVE to bring to the beach, it is "hammock style", easy to blow up.  Also consider a few travel games. For my 9 year old niece we had boggle, yahtzee and Uno, she was very happy at dinner that we had something to do together, even a deck of cards can go  a long way.  


 

It's going to be tight. 
There is probably room for a pack n play but there won't be much room to move around when you are done.
It's pretty late to move rooms now and I certainly wouldn't count on a Royal Up.  If you were able, I would add an extra inside cabin or adjacent cabin and have the 2 teens in that room.  You would need to book an adult in each room, but could rearrange the occupants once you board.

I’m not much help with the teens, but here’s a recent post relevant to the baby!
 

Thank you @AlohaLivin you are correct, they are booked all of 2022. I waited way to long to look into getting hitched on the ship. Thanks.