Brush: Best for edges and detail work. Roller: Fast for large areas (back-brush afterward). Sprayer: Efficient but requires masking and back-brushing.

Soak in vinegar (for latex paint) or paint thinner (for oil-based) for an hour, then comb out residue with a brush comb.

No—always dedicate brushes to one type of product (paint, stain, or varnish) to avoid contamination and poor results.