Regarding searching that is done through the extensions own search module. I suppose you could restricting search criteria or keywords using By URL Part protection. You can also restrict directory categories or entries using By URL Part protection. As you already have a CBSubs license it's best to simply test these usages and see what works best. CBSubs can not add features to an extension that do not exist so if there isn't a way to implement the protection with queries or say By URL Part protection then it probably can't be done.