Yeeesh, now I'm confused.
If I want to add remote start buttons for my PC and monitor, which of the following two buttons should I use?
- Closed as long as you're pressing the button
- Closed only briefly when the button is pressed
I intenionally did not use the word "moment" 
For the PC, this depends on what type of motherboard/power supply you have.
MOST anything current is ATX standard. THese use a pushbutton like what you would have on your CP(the 1st type above). Push the button, it sends a signal to the mobo, power comes on. Push it again, it sends another signal and power goes out
AT standard uses a button that pushes in and 'latches', maintaining contact. When you push it again and unlatch it, the circuit is opened and power is lost.