Analog inputs?

Just about any joystick/gamepad that works with Windows should work with PJ64. And yes, PJ64 will work with four controllers.

As long as you have a USB for each controller, and the devices are properly installed.

yeah, dont forget to enable analogue on your controller when your inputing your config otherwise it will be digital.

I just bought a wireless Xbox 360 receiver for $20 and it supports 4 wireless Xbox controllers with one receiver. The controllers are pricey but I already had a couple so it was no loss. They're far better than a lot of PC gamepads though. Setting up N64 controls isn't a big deal the only odd thing is I set the C-Buttons to the right analog stick which takes a short time to get use to but works sufficiently. Previously I was using a Playstation controller and USB adapter. It was similar in operation but the analog sticks seemed to be too sensitive most of the time (probably due to my specific USB converter).