Custom Legend and population calculations

The data that I work with requires population calculations in order be uniform but it can a hassle to create a separate column with manual calculations each time I want to view the configuration (e.g., per 1000 people, percentages or prevalence). Additionally, it's near impossible to customize and label the color scale, ranges, and legend the way I need it. It becomes harder to create standardized outputs for scientific journals or reports that have both print and web requirements.

It would be great if #399 was built out more to support legend configuration and manual configurations of scales. Ideally, having a method to link or export to QGIS to create finalized and detailed map legends and outputs would be a really helpful solution if it's not possible on the platform.

My head spins thinking about how to recreate my Kepler maps in anything that's not as beautiful and effortless to use. I just need some help crossing the finish line to a final product.