With 3-day park to park with early entry and EP you won't have any trouble seeing everything you want and many things more than once. I guess it must be spring break time since some of the APs have blockout days then. It's been awhile since I've stayed at Royal Pacific but if you get to the boat and lines are really long you can walk to the park. The path comes out between Margaritaville and IOA. Maybe someone that was there last year at spring break could say more specifically how bad the lines are for the boats early am. Getting in the full hour of early entry is important. I was there with my family at Thanksgiving without EPs but I have Premier pass for early entry. We went to Minions first since I knew lines later w/ no EP would be crazy. We got to Gringotts by 8:20 and waited in line an hour before getting on the ride. The only comfort we had was that technically if they hadn't got in early it would have been way worse. There are limited rides open at early entry so you can only ride those for the first hour and look around.
If you want to go to the Olivander's wand shop show go to the Studios side. They have many more shows running and less wait - there are also no EPs taken here. You'll see the huge line at IOA for this - it's crazy. The early entry schedule isn't up yet for you timeframe so just check back in a week or so for planning.
https://ww2.universalorlando.com/web/en/us/early-park-admission/index.html#universal-studios-florida
I like to ride the HP train at the end of the early entry time since the lines are short plus is doesn't take EPs. When it's not crowded you can take time through the line. Just let people go past you if you're stopping to take pics and don't feel like you have to rush through. The line is half the fun of the ride. The train holds a ton of people so you will likely be on the same train as all the people that may go past you. My first trip after the train opened (in the afternoon) I waited in line 45 minutes - at a slow time of the year. Now if I switch parks and the train line is long I just go out to CityWalk and walk around.
If it gets really crazy during the day you can always go back to the hotel or just go out to CityWalk. You can also take the boats to other hotels. I noticed the parks are open 9 am to 10 pm during your trip; those are long days. There is also an AMC movie theater at CityWalk.
Another tip would be that if you want to see the Cinematic Spectacular show do that the first night. Then on the other days during that time you can go into the HP areas when it will be much less crowded. Easier to take pics or use your wands w/o as much of a line. I personally don't care for this night show. They project old movie clips onto falling water and have fireworks. You definitely don't need to see it more than once.
Here is a link to height requirements.
https://ww2.universalorlando.com/we...ts/index.html#universals-islands-of-adventure
I almost forgot since I've never ridden it but if you want to go on Ptaradon Flyers there's some type of ticket thing that you get then come back at a certain time. If your little ones want to ride you might do a specific search for it. Or just check it out your first day and if it doesn't work out try again another day.
Don't forget to go to the Dinosaur Encounter in Jurassic Park. It's toward the HP side near the Discovery Center I think it's called. There will also be a long line for this if you wait, no EPs here either. It usually opens around 10 am. You can check it out on
Youtube. They take pics with your camera for you also. There is a place behind Discovery Center where you can get good pics of the park across the water. It's never busy since it's off the main area.
I've also never done this but I think there is a line through Forbidden Journey you can walk through to just take pics and not ride.