I'm sure the crowds won't be too bad at all that day since it is a weekday and schools are in, but since it is during there Christmas celebration(only on select days, polar express will probably still be open that day), I would recommend you ride the Polar express during or before the killer whale show, after that show ends everyone flocks to to the Polar express and makes a long wait.
For the coasters, I really don't think you'll have much of a problem, the longest wait you usually have is on manta(i hour tops on weekends), so if your coming in the morning I would ride that first, every time I have been to SeaWorld recently mako and Kraken have had very little wait, since Kraken isn't too popular and mako has a really good capacity.
Also, if Empire of the penguins has little to no wait(typically only in the morning), sure, go for it, but if it has a line it's really not worth waiting in, and even on slow days, it has a line that moves super slow. There is a separate line if you just want to see the penguins though that's usually shorter
The sky tower and journey to Atlantis will probably be closed during that time. Journey to Atlantis closes every winter for a refurbishment and the sky tower... Well... I don't know why but it's been closed for 3 months straight and I don't expect it to open for thr rest of the year.
Even on weekends I only spend 2-4 hours there and I usually get to ride everything. So im sure 5 hours will be enough, especially on a weekday.
