Is it possible to replace the rear brake drums and put Brake pads and calipers on it?
May sound like a newbie question but just never heard of it.

yes, anything is doable, but there is a considerable ammount of work and uncharted territory. in order to do so, you would have to get hubs, pads, rotos, calipes, caliper brackets, new brake lines, new proportioning valve, and hope that they all fit because its never been doen before, after that you may or may not have a fully functioning ABS or Traction control system