I would rather give money to a needy person directly than to a charity. In other words, I'd give money to a sign holder before I'd put it in the pocket of a charity executive.
Yes, it does. I would want to make sure that the largest percentage of what they receive is used to fulfill their mission rather than for administrative costs or fund-raising events.
Yes. Many large charities spend a great deal on overhead, including large salaries, lavish offices, and fundraising rather than on the people/cause they are supposed to be helping. Sometimes the money is spent on something completely different than one might naturally think, such as the National Humane Society concentrating on laws rather than care of animals in shelters.
I have always preferred small, local charities I am familiar with and helping people directly. If someone has a particular need I can fill, I will do so. If they request or I offer money, once I have given it, it is theirs to do with as they wish.