Best Map Visualisation to use

Without playing with your data, I would say you could possibly map total sales per city, then filter by product using a slicer.

For your third requirement, do you want to know which city is selling the most/least of a certain product or which products are selling the most in a certain city? These would be two different visuals and your probably best going down the bar/column chart approach. You could try a tree map, but its likely to be too busy. You could also exprimement with TopN filtering to decease the clutter.

Just some thoughts.