About a quatre of a large yellow bucket.
As for making the mix wetter, im using a small tile on a flat floor with no build so I personally prefer my mix a tad more smoother as I feel its gets better coverage/stick on back of tile.
Ive not made a stiffer mix with it yet so couldnt really comment on that but id imagine from using it that aslong as its not very stiff then it would spread just fine.
Id also imagine the brand of adhesive could also make a difference with regards to stiffness as some adhesives such as webber and granfix are smoother like a chewy when mixed and brit adhesives and mapei tend to be more sandy/gritty in texture
