You know that people don't always know what address they are sending from right?
Your form asks for the sending address. Most people won't be able to predict that.
As the administrator I will collect no more than 40% of the total collected amount (Normally will be 25%). 20% will be donated to a charitable organization via
www.bitcoin-charity.com.
Hmmm, 5%-20% is yours! Or is it 25%-40% while another 20% is donated?