30k should work for the pullup resistor. It's adequate to drain away rogue charge at the transistor bias. And sufficiently high that it won't interfere with pull-down signal from the comparator.
As for +ve and -ve, I'm not sure what pins these refer to, but going to the databook diagram... The unused inputs on the 339 are pins 4, 5, 8, 9, 10, 11. These should be tied to ground according to the databook.
You do not need to connect anything to unused output pins 2, 13, 14.