Because of its permanence, the acrylic should be cleaned from the palette at the end of each painting session. Rubbing alcohol is a good cleaner. Personally, I use white styrofoam trays as an acrylics palette. They can be disposed of after each painting period. A s long as they are cleaned immediately after use, watercolour brushes can be used for painting in acrylics.
Acrylics are permanent.
Paint left to dry on a brush cannot be removed. I do not use my sable brushes but, I do use synthetic, softhair brushes that I also use in watercolour. A crylics come in different thicknesses or viscosity. Heavy body acrylics come in rubes and jars. The viscosity should be indicated on the jar.