Short answer, the ohmage of the pots used has an effect on the tone, the higher the value of the pots used the less treble loss you get. There's usually a choice of 3 different values, 1meg, 500k, and 250k. 250k are usually used in single coil arrangements since singles are naturally quite trebly and they help cut the treble down a bit, they may cause a humbucker to sound excessively dark though. 1 Meg is sometimes used with humbuckers since due to design they're generally dark sounding compared to singles. 500k is a halfway house and standard fit in LPs. I'd tend to just follow convention and use 500k for humbuckers and 250k for singles unless you really know what you're doing ;).
In terms of easiness, as long as you're reasonably competent with a soldering iron and can follow a diagram you should be fine. Expect it to take 3 times longer than you think it will if you've never done it before though ;).
