I don't understand. You're afraid that your Google searches will be published to your Facebook stream, so you want to close your FB account and move to G+, because presumably Google is less likely to publish to your G+ profile than to your Facebook profile?
I'm with you there, which is why I've closed my FB profile long ago, and my G+ profile within the first day (as soon as it forced me to link Picasa).
G+ makes as little sense for a private person as Facebook, if not even less.
Wouldn't it be easier just to continue using Facebook, but never grant any permissions to any apps?
On another note, I'm seriously considering closing my FB account once and for good and leaving for G+. I have a good crowd of friends willing to do this (and invite their friends), but G+ offers no way to import FB data, which would be a nice feature.