365939 Magento PHP Customization

We run a t-shirt store using Magento. Here is what we need Magento to do: On the product detail page, we need to have the sizes for each shirt, with each size is a different price. For each shirt size, there should be a quantity box so that they can enter the number of each size shirt that they want. Once they add the quantity, the system will calculate the price. It would be better if the sizes went across horizontal. Next, I need the system to allow up to 15 custom options when adding a product in the admin area. Currently, it seems to limit me to 10.