First of all, good luck on your interview!
Like any town, there are ups and downs...pros and cons. The pros far outweigh the cons in Yankton.
I moved here from Lincoln, Nebraska (pop. 125,000) to Yankton (pop. 13,500) and had to adjust to the quiet and lack of major shopping options.
What I have found in the last 12 years of living here is that it is almost a paradise for raising kids here. Our kids ride their bikes to the park, swim at the lake, play baseball on a sunny day; without fear. This is not something we would let them do so freely in Lincoln.
Yankton is virtually violent crime free. In the 12 years I have lived here, there have only been 2 shootings. While that is still 2 to many, that is an unusually low number by todays standards. Reading the public record in the local paper (P & D) you will see that most of the arrests are petty crimes ( DUI, trespassing, shoplifting, etc.) But violent crime is very rare.
Some people on this board like to mention that there is a meth problem in Yankton. There is not any more problem than any town in the US. Again, in 12 years, I have not been in one scenario where there was meth involved. It all depends on the crowd you run with.
What you and your kids will love about Yankton....Lewis and Clark lake! A beautiful and very well kept lake and campground. It is the pride of Yankton and a source of tourists dollars. We are at the lake at least 3 days a week during the summer. If you love to camp, boat, bike, sit in the sand and drink a beer, anything outdoors, you will love the lake. There is a great bike trail at the lake and hiking paths in the woods. The staff at the Lake keep the area very clean and well attended to. On the weekends there are lake activities and programs for the kids (geocaching, etc.) and outdoor movies and popcorn at night. The Marina at the lake has great food and a wonderful outdoor seating area to watch the boats while you eat.
There is, of course, a Wal-mart and K-mart in town. There are not a lot of other chain stores, which is probably for the better. There are several locally owned business, lots of antique stores, fabric store, resturants, grocery stores (with a Starbucks inside) a great library,a museum,and so on. Yankton could use a coffee shop. There are a lot of parks in Yankton. The outdoors is a big part of living here. They are all very clean and very safe.
In the late Summer there is Riverboat Days, a weekend celebration of Yankton with vendors, LOTS of food, music and activities. I think they estimate 100,000 people attend each year. Early fall will be the 3rd Rib Fest in downtown Yankton. Great food and the streets downtown are closed for eating and drinking.
The winters here get very cold and there is not as much to do here as in the summer, which is probably where there are a lot of June and July birthdays

The population seems to stay put, not a lot of growth, mostly because a lack of job incentives to keep high school graduates in the area or college grads from moving back. We are going through a higher than state average of unemployment right now, hopefull that will change soon.
The schools here are top notch; very progressive with technology.
In summary ( I am getting a little long winded here) Yankton is the ideal place to raise children. It is very clean,
very safe, very little crime, and there is a lot to do in the summer. I have been all over the country many times over and this is probably the best family oriented community I have lived in. There are always worries when it comes to your kids, but just a little less here.
Hope that helps!