What's the best course of action for this wall?

[theandroids]

No need to skim, if you are going to board over, use a SBR or tile primer, stick pro warm or what ever you want to use with a s1 tile adhesive, Wack a few screws in, then tile

Will do.

 

[theandroids]

Just an update for anyone like myself with a similar situation who might read this thread.

I've been told by British Gypsum to use
Thistle Bonding 60 if you want to repair this kind of damage, before installing backing board.

 

[Waluigi]

60 being the time it takes to set I assume? Never used it.

I prefer to use dirty water or a handful of cement in the mix if I want to patch up quickly.