Transistor for a camera/powered circuit

Hi,

Opening caveat: my electronics knowledge is pretty basic, I appreciate any help.

I've pulled apart an action camera and soldered some wires to the switch contacts for the power/function button and the shutter button. For both switches when I touch the pair together it functions the same as the button (success!). So what I want to do is use an Arduino to control each of these. I'm assuming a transistor each switch will work (would relays be better?). Others have done the same, but I'm struggling to understand their methods.

I've got some of these transistors: BC547 NPN transistor. I can't figure out the wiring because the examples I can find use the Arduino to power whatever the transistor is controlling, whereas this already has its own power source.

Questions:
-Is the transistor above appropriate for this purpose?
-How do I figure out what resistor to use? Is it based on the transistor or the circuit the transistor is controlling?
-I'm assuming I can't just connect the transistor Base to a digital output (with a resistor) and run the two switch wires through the transistor Emitter and Collector? Or do I need to connect the Emitter to the Arduino ground and one of the switch wires? As in this diagram

If anyone could help, or point me towards a more appropriate guide.

Thanks

The safest and easiest way is to use a tiny reed relay.

This one can connect directly to a 5V Arduino GPIO. Connect pin 2 to any GPIO, connect Pin 3 to GND. Connect the camera wires to Pins 1 and 4, either way, it's not polarized.

Thanks very much. I've ordered those reed relays, but they'll take a while to arrive. In the meantime I found an 8 pin reed relay with similar characteristics, and after a bit of mucking around with the timing it worked fine.

Thanks for the help!

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