Your oscilloscope is your best friend here. Anything more than about 1 volt p-p noise needs to be fixed. Sometimes adding power supply bypassing can actually make a project not work. The way this happens is that the ground distribution system is high impedance, and the addition of the decoupling capacitors makes the current in the ground lines higher, leading to ground noise. Since the noise margin in the low state is worse than in the high state, this can be a bad tradeoff.
Ground is easy to come by.
The resistor value is non-critical, somewhere in the range of 1K. Many inputs can be wires in parallel to this resistor. Making the run extremely long can be bad from the standpoint of finding errors. It is common, and the source of difficult problems, for the high run to have some output connected to it. Since you often pull up sets and clears on widely distributed circuits, this can cause very bizarre behavior. The behavior of parts which do not have a ground pin connected can be quite disconcerting.