F! is a very great show that has been running for almost 20 years at the ROA at night. One of my favorite nighttime shows at the DLR. It features fireworks, actors, water effects, fire, floats, boats (Mark Twain and Columbia) and projections on large mist screens and But it can be scary for little kids with the evil villains, the loud noise of the fireworks and canons shots on the Columbia during the PP scene.
As for your day on Friday the 21st, I will be there on that same day and I might run into you. As for the tip if you want the best viewing area of the show it is right next to the railings of the roa. You will have to sit down and there is no standing in the sitting area right next to the railings. People show up at least 3+ hours for the railing sitting area and the whole viewing sitting area fills up at least one hour before the 1st show starts. But since it is during the slow season, you can get a front spot around 2 hours. If you have strollers, you will have to fold them up and put them down before the show starts or you can leave it up if you sit in the back area of the sitting area. You can have a stroller or a wheel chair right next to the rope area. And
definitely bring a blanket, so you can mark up your area for your entire group and some of your party can go on rides or get food while at least one person can sit down on the blanket and watch it while others of your party do other activities. This would tell people that you are saving a spot for your family.
Here is a picture of the guests waiting in the sitting area by the ROA for the 9pm F! show at 9pm last August. This was like 2+ hour wait around the time I took the picture, but it should not be that crowded during this time of the year. I have never been to DL during January which is the off-season so I dont know what it will be like. So I just plan it as a summer time when I watch F! at DL.
A lot of the DISers would say they would not do the 1st show and just do the 2nd show instead of the 1st show. But I would guess that since you have young kids, it would be good to do the first show. Since when the fireworks ends, the CMs instruct the guests that are leaving the ROA to head towards the Adventureland side to exit the park. Sometimes people want to see F! again and the people who did not have a good view to watch F, they just move up closer for their group. Most of the people watching the fireworks from the hub come through the Frontierland area and the guests have to wait until most of the guests that watch F! have cleared the area. Some people also wait when they are in Critter Country and head over to the viewing area when everyone is moving. It's another good way to watch F! if people are not wanting to wait for hours to see the first show of F!.
Another good tip is the
Light Tower Trick posted by S.S. Columbia, if people don't want to wait a long time for a good spot.
There are millions of hints and tips that I can go on and on. But there are other DISers who have better tips than me.
I'm so excited for the show 
This is not Phantom of the Opera for goodness sake. Is that the right amount or a typo?
