Ours warmed it a bit for the first few months and then he didn't seem to care so he drank it cold. I would have them try it cold first just to see because it's nice to have that flexibility, but if it doesn't work they can always warm it.
For #1, they warmed it in a cup of warm water. The put formula bottles in a crock pot of water, but I had noticed when I did my original walk through that the water in the crock pot was boiling, so I specifically told them NO crock pot warming!!
Re: If you work and pump ...