Re: pumping for friend's baby?
You will probably be able to get quite a bit of milk out, but it may be slow to start. Do you have a double pumping electric pump? If you could rent a hospital grade pump, that would be even better. The main thing is to be consistent about timing. I would start off pumping once a day, first thing in the morning until you get used to it and then adding more sessions as you want.
Would you like to totally get him off formula? Or just supplement him with your milk? You would need to produce around 24 ounces a day for him to get him completely off of formula. That might be difficult, but I bet you could easily get to 12 ounces or so.
ETA: It's so sweet of you to consider doing this for your friend's little boy
Lilah 10/08 nursed 25 months
Beatrix 01/11 nursed 30 months