These are all valid questions, and should absolutely be considered before donating to a charity. However, it's difficult to determine exactly which charities do the best in terms of using your money for how you intend it to be used. Sometimes the information to answer these questions isn't available through a charity's website, and therefore you're stuck. At that point, the questions comes down to: Do you donate, and risk having a large percentage of your donation go to administrative costs of the charity? Or do you forget making a contribution all together?
However, there are ways of determining which charities do a good job at handling donations wisely and the way that donators intend their money to be used. Websites such as Charity Navigator help you determine all the answers to those hard to answer questions. Especially recently, people want to donate to charities to help Haiti, and many people aren't considering other implications when it comes to donating--but they should.
What if you donate $100 to an organization that states it's mission is to help get prosthetics to people who lost limbs from the earthquake, collapsing buildings, and other objects in Haiti. Not all of that $100 donation is going to go directly to purchasing a prosthetic for a person who lost a leg or an arm. There is a percentage of that donation that goes to administrative costs. There is typically also a percentage that goes to fundraising efforts. Yes, you read that right--fundraising. Although it may be hard to believe, it does COST something in order to RAISE more money, so there is a fundraising cost for many charities. Then there are other various expenses that programs also have. And this is all before money goes to the actual program means.
Charities NEED to have these preliminary expenses, though. It's important for a charity to have fundraising efforts, administrative components, and other program components, because without them, the charity would not exist. However, some charities are much more effective and efficient than others in terms of how donations and partitioned, which is why it's important to RESEARCH a charity BEFORE you donate.
Using websites like Charity Navigator is a great way to do so.
So before you give, get informed! It's important, and it's the best way to know that your money is going to do the most amount of good possible!