You can start to teach 'holding breath when water is on your face' by just scooping up a handful of water and pouring it over her face. Make sure she sees your smiling happy face when she looks at you, if you look worried she will be scared! You can always say the same words before she gets water on her face, then she'll learn to hold her breath when she hears them, and you can let her go under breifly ie when she jumps in.
Re walking hands along the wall, you hold her hands and 'walk' them along. We do it with a rhyme: Monkey monkey monkey, climb along the wall, Monkey monkey monkey, don't you go and fall. Now when we say 'monkey monkey', he starts to use his hands to pull himself along the wall. Like with all these things, it is loads of practice and consistency, we've been doing this since Stan was 3 months old.