Bathroom Best Course of Action 100 X 300 MM tiling - Tile Advice

[theandroids]

Hi, can anyone tell me the best course of action before tiling on these walls? The majority is drywall that I have removed paint and tiles from. Have not really damaged the drywall to the extent of replacing them completely, just a gouge here and there. Can I tile over this or do I have to do something else prior to doing so? Eg. PVA, Ardex feather finish, Thistle Multi-finish, liquid tanking etc. What would you do?

 

[White Room]

If this is within the shower area will you be removing the remaining tiles.

 

[theandroids]

If this is within the shower area will you be removing the remaining tiles.

If this is within the shower area will you be removing the remaining tiles.

Did all that. The picture is just to show whats underneath.