I need to sell my extension on magento connect. It is a paid extension. How I get payment, when some one buy my extension ? Do i need to get the payment directly from buyer or from magento ? how much I need to pay to magento, when some buy my extension ?
Magento connect redirect user to your site (you define link for payment extension). After that you should take care about payment processing by your own
Maybe you can start here to understand the new Marketplace: http://docs.magento.com/marketplace/user_guide/getting-started/faq.html