I pay support to my ex-spouse. I think he should have to use the support to buy the kids clothes, books, sporting equipment, and all that. He says I still have to buy things for the kids even though I pay support. Do I?

The short answer is yes. The child support formula (used to calculate your support based on your income) assumes that each parent provides things for the children when the children are with that parent. This means that both parents have to buy some clothes, and some food, and pay for some school lunches.