For picking out icons, I like to use the noun project. It has thousands of icons you can choose from, and you can you can even recolor your icons before you download them (this is a new feature that I particularly like)!
I also like using the data visualization catalogue to help me think through the different options for examining relationships and visualizing them.
For building dashboards, my favorite program is tableau. There is a bit of learning curve to the software, but it is an incredibly powerful software with advanced features for data visualization, including maps, charts and pivot tables which can bring meaning to data if properly configured.
