Hi I am after some advice, I am in the process of removing and replacing the old tiles in my kitchen (spashback). During the removal process, some of the old adhesive pealed the paper off the gyprock (Thin layer left, no chalk exposed) , some small holes occurred and few small minor dents. I have filled these in with Selleys Spakfilla Rapid and sanded. Picture below - the white plaster above the PowerPoint and stretching right across is previous filler and not exposed gyprock. Dark brown paper is the deepest the exposure goes apart from the wholes and dents.
Do I need to / should I prep the wall before using the Dunlop Wall Tile Adhesive. Ie Do i need to prime/paint the wall before tiling with a multipurpose primer such as the Dunlop Multipurpose Water Based Primer?
Also I will be tiling over the previous painted surface, short of cleaning with sugar soap is there anything I should do to the wall to prep for the adhesive/wall tile?

Many Thanks Maf.