3 pounds is a good number - and that's exactly what pull most of my Remington's have.
As for the work that is involved, I really can't tell you. What I can tell you is that I send my rifles to a competent gun smith to do the trigger job - which not only adjusts the pull weight, but also takes out the creep as well. There is some grinding involved and the cost is usually no more than $50. To me, it's worth it because the trigger is a critical part of the safety of the rifle.
I know that several people adjust their own triggers on their rifles. While I myself do it on my Tikkas and Sakos (which is essentially idiot proof and doesn't require anything other than just turning a screw to adjust the pull weight) I wouldn't recommend doing it yourself on a remington or winchester.
Zachary