I recently came across Amazon AWS hosting and other things offered by them, and noticed quite a few big guys host there.
What does it cost to host with them. Are these guys same as our conventional hosting guys (who give you a control panel and then you setup your databases, upload files to your root) or are these guys different?
You pay by usage. Storage usage is measured in GB. Server usage is measured in hours you have a particular server instance active.
On the server side you have an "on demand" instance or a "reserved" instance. A reserved instance is useful if you will have something running full time over the course of a month/year. You pay less for a reserved instance. On Demand instances are good if you need to spin up a temp server for testing or when load demands additional capacity for a somewhat limited time.