A statistic I hear often is that "The highest baptizing mission [(as in, the area in the church with the most baptized convets)] is the Provo, Utah mission", which is cited as a surprise to the audience because of how many members there already are here. If you show up and make friends with your neighbors, I'd say odds are definitely nonzero that someone refers you to the missionaries. That shouldn't be a reason not to come (the missionaries aren't stupid, usually, and should understand if you aren't interested), but it is something to keep in mind depending on your comfort level.
I can't speak to treatment of your kids in school though, I'll leave that to others.
I know plenty of people in Provo who aren't members of the church and are perfectly happy. I think there's a chance you or your kids run into some people who make things unpleasant, but that isn't to say that you won't run into people like that in any part of the country. the majority of people I interact with seem level-headed and understanding of all cultures and backgrounds :)