As far as overpopulation, the US is actually approaching zero population growth.
It makes sense to care for the hungry and the sick. It's part of my value system. If the richest and most powerful nation on the earth can't be humane, then there is no hope and we might just as well go back to the jungle.
I think the problem with this is that we aren't just caring for the hungry and the sick - we are caring for the lazy and stupid too. And from what I have seen, we aren't doing a great job of caring for the sick and hungry (especially children and vets) because we are spending so much money on the lazy and stupid.
Most of my feelings on foodstamps/welfare comes from the people I have known on it - most of whom, imo, were scamming the system. For example, I knew someone who was 14 and looking to get pregnant so that she could drop out of school and have money to party with. Taking care of a kid was her last concern, but she knew she'd get money for having one. Another example, someone on food stamps who had 8 kids - being on food stamps starting with the first one but instead of using protection to not have kids, kept having them. Another, someone who was physically able to work but figured he's milk his "injury" as long as possible - he was able to do everything (go out for beer, see movies, buy stuff, etc) except work.
Going on those examples, the money seemed to be spent there. However, the people that I knew that really needed the money (mostly children from abused homes), it was hard to get any money for them - the money would go to their parents (who no longer had custody or at least didn't have the children living with them) or the money just wasn't there.