1) Regarding chametz, unless you are chassidishe or yekkish you don’t have to worry about it. Before the Blumenkrantz book came along, (ie, in Europe) the Litvaks never worried about things like perfume and the like. Playdough is not an issue either (and I heard this from my Rav). (BTW, the whole issue of Litvish vs. Chassidishe can be seen when the CRC (Chicago) comes out with their Pesach list and it’s two pages and the Blumenkrantz book is hundreds of pages.)
2) You don’t need to worry about your kids eating it, it’s not food. If you do worry about it, then you should also worry about glue and most other things kids touch.
Please see note by squeak a few posts down – YWMod