Winsor & Newton 0308744 Water Colour Tube, Yellow Ochre, 21 ml (Pack of 1)

Can these be washed off?

I have mostly qor paints and i'm looking to slowly shift to winsor and newton. do you think they will mix with qor watercolors fine?

This is student grade Cotman paint - why is it over $10? Michaels has this in professional grade for the same price.

Will i get good results if i mix daniel smith iridescent paint with this, or glaze over dry w&n paint on paper with ds iridescent watercolor paint?