Yes and no. Short answer is you need to apply a bonding agent to the durock so the plaster will stick. Blueboard is chemically treated to accept plaster, durock is not so it will just fall off without a bonding agent.
No, it must be screwed. - But there are many varieties of excellent concrete board now. -
If one side of the drywall is green, it is actually green board. Green board is made with concrete, and is intended for high humidity areas. It will not mold or mildew the same way normal drywall will in moist conditions.
To cut Durock cement board effectively, use a carbide-tipped scoring tool to score the board along the desired cut line. Then, snap the board along the scored line. Finally, use a utility knife to cut through the mesh on the backside of the board to complete the cut. Remember to wear safety goggles and a dust mask when cutting Durock cement board.
No, it is better caulked with a water resistant caulk. ( Also it should be at least water resistant drywall or concrete/fibre board.)
You COULD, but there's no real need to.
If you expect your shower to last, then remove that drywall and re-finish it with concrete/fibre board. It's so much better than drywall you wouldn't believe it. Nobody professional does drywall around a shower anymore.
If you want to do a really good, lasting job, use concrete/fibre board (Green board) instead of drywall. It comes in 30x60 sheets, about the same cost as drywall, easy to work with , totally water resistant and excellent for tiling. About 4-5 kinds available, Rona and HD each have 2-3 types.
When covering existing walls with structurally sound surfaces, you would typically use regular gypsum board, also known as drywall. This type of drywall can be easily installed over existing walls to provide a smooth and even finish. Make sure to choose the appropriate thickness depending on the application and follow local building codes for proper installation.
White is the colour of standard drywall board
Cement board, at most contractor supply places it will be called DUROCK cement board or Permabase cement board. = =
Replace the drywall with tile backer.
That's definitely a good idea. If there is a sink and tub in there,I would even use a concrete or fibre board to back them also.