Excellent article..

A couple of minor points:

1. Giving $1 to a charity can serve the purpose of stating ones support and endorsement. This is an argument for getting lots of people to give that $1.

2. Giving "parochially" can help if you have better information as to the effectiveness of your donations, e.g. if money to help the poor is being handled by a neighbor you know well and trust. Of course, this consideration can be dominated by others like the greater effect of money to the extreme poor.

But your points are quite correct.