The easiest way to restrict it to those that have identified for their nicks, is to set the channel mode +R (UnrealIRCd, and I think most if not all others). The one problem that this creates, is the fact that non-registered users on the network won't even be able to join the channel.

As to the !kb command being run, edit your !kb script to check if the nick sending the command is the bot running this script and if it is, then ignore the command. Alternatively, you could put this script on the other bot, then it won't conflict, since your bot won't recognize the message being sent since it's sending it.