Opinions/Advice

Hey everyone, I'm new here so let me introduce myself. I'm Terminus and i hope i can learn a lot from you guys
But I digress... what I really need to ask is for some advice/ help. I'm doing a small time project ( im trying to start of kinda small ) and making a simple lie detector ( actually following this main design --> **broken link removed**). Now what i want to know is ... if i want to make my own modifications to this circuit such as adding an external circuit to control the main one, where would the proper place be to add the connections leading away to the switch? This part confuses me - when i think how ill do it, that is. How can I ensure the current will be controlled by the switch (that is when I open it, it operates normally, but when I close it, it follows the external circuit and sounds the speaker.) Just a small experiment i want to do but for some reason i cant work myself around it Help needed to get the brain juices flowing...
On a side note, if i want to use a wireless control, encoding with assembly will be necessary am i right? Just need a confirmation. Thanks in advance!