I don't see any schedule up yet for the kids activities, but sort of things they've done in the past for similar "festivals"-
storytimes (usually with a local Maine author, eg tie in to get the books {I don't mean that in any bad way- my friend got alot of her books sold that way!)
Gingerbread cookie decorating
make a simple ornament
Meet LLBear
Most tend to be in 2 hour or so blocks, but it's something the kids would be doing for maybe 10 minutes. I might stop in if I had to pick something up in Freeport and had the kids along. Truthfully, not such a big deal I'd plan as a fun outing for the kids. (It'd be more like "let me shop 2 hours and we'll stop in here for 5 minutes

) The hayride things are usually a horse drawn wagon up/down Main St. Again, a fun diversion, but not a huge destination thing.
Freeport in Dec is alot colder than summer
If you are up this way, the Narrow Gauge Railroad in Portland has started doing a Polar Express ride. I've never done it as my kids are too familiar with the route to believe they are going to the North Pole

but I've heard it is fun.