To answer your Need to Knows, you may have to make direct contact with people who have access to public records, as Solvay does not have an extensive web portal. Begin with what you can find online, but as you go, generate questions so that you know what to ask when you get in touch with people.
There have been a number of books published on Solvay's history. Browsing them might give you an idea of who you could contact and interview, as well as help you generate a list of businesses and community institutions that Solvay was founded on. These will be on a cart in the computer lab for the duration of this project.