(1) From the meaning of the question, the relationship between monthly sales volume and sales unit price can be approximately regarded as a linear function, and profit = (pricing-purchase price) × sales volume, thus listing the relationship;

(2) Let w=2000, and then solve the quadratic equation of one variable, so as to get the sales unit price;

(3) Calculate the monthly expenses according to the properties and images of parabola.

I hope this helps.