If you don't have enough balance in PayPal, you just can load money in your PayPal from your bank by linking your bank account with PayPal about which you can ask with PayPal team for details. PayPal provided the support staff for each country so that you can ask them in your own country language by using contact as provided in their website which you can find by clicking "contact" on the bottom of PayPal page.
Affiliates decide within their affiliate programs which banners or ads they're going to place on their websites. This decision is based on their individual calculations of which company ads their website visitors are most likely to be interested in. They will also agree to affiliate programs based on which merchants have the best commission structure, although the structure is not usually considered very high-paying or profitable.