You could use pwm, lookup arduino, there is a pid library available for the arduino, this would be ideal for temp control, the library comes with a example to control a relay fo thermal control, a laminator has a high time constant so slow on/off ought to work.
Theres probably a library for current loop control to drive your i to p valve.
Edit: reread your post you say functions are to run on a pc, well you could still use the'duino for i/o and do the rest on te pc, the 'duino has usb to rs232 on board.