Riverside is a nice little town, about 20-30 minutes from Iowa City on four-lane highway. It's growing pretty quickly, as a lot of towns around IC are. Riverside has it's own school district, so you're looking at a very small school. I haven't heard much about Riverside schools, so that probably means, as best I can guess, they're about average. Of course, average for Iowa is still pretty good compared to other places!
I've always been partial to Solon, Amana and North Liberty over the southern areas myself. I've heard good things about Solon and CCA schools particularly--and both are building brand new buildings.
I don't believe Iowa has an all-day kindergarten law, but I think most bigger schools offer it. Of course there's always the private schools in IC too.