Helloooooo
Characters you will meet is tough - the line-ups aren't guaranteed from year-to-year, so I wouldn't bank on seeing any particular ones. The only guarantees I feel confident about are during the half - there will almost surely be some villains meet, almost surely a Pirates of the Caribbean meet (with a big ship) and there will almost surely be some "heroes" meet (i.e. Prince Eric, Hercules, Tarzen, etc.). These are ones I've seen repeated in trip reports quite a bit.
As for the race courses...
- The 5K goes through Epcot (part of World Showcase and Future World)
- The 10K goes through Epcot (part of World Showcase), the Epcot resort area and then back into Epcot (Future World)
- The half marathon starts outside of Epcot - goes to Magic Kingdom (Main Street, Tomorrowland, Fantasyland, through the castle, Liberty Square, Frontierland) and then to Epcot (Future World Only)
I totally think you could do the 5K!! I have done this course a couple of times and it's really fun.
It is NOT sold out already. On Tuesday 6/30, early registration for AP/DVC opened. These early slots are about 5-10% of total registration - only the early slots for the Glass Slipper Challenge (the 10K + half marathon) and the 10K are gone. So as an AP holder, you could go ahead and log on right now to register yourself for the 5K and your DD or DH for the half - UNLESS they want to do the Glass Slipper Challenge. They will have to wait for that.
Now, regular registration opens on July 14 at noon EST. There will be slots available for the 10K and Glass Slipper Challenge.
So first of all, your DH/DD need to decide if they want to do the 10K, the half, or both...
- If they decide on the half and NOT the 10K, they could sign up for that now - there are still early spots open for the half.
- If they decide on the 10K and NOT the half, they need to be ready to go right at noon on July 14 to sign up. The 10K is very popular and will fill quickly (like, within the hour).
- If they want to do both the 10K AND the half, make sure they sign up for the Glass Slipper Challenge - if they sign up for the 2 races separately they will not get the GSC medal and shirt. And if they do go for the GSC, just like the 10K, they need to be ready right at noon - GSC will fill up the quickest of any of these races, except maybe the 10K.
I hope this helps!!
I'd look around here for trip reports on Princess Half Weekend...those should give you a good idea of what to expect from the races.