Why did the Mennonites and Amish use the first names of their founders, as opposed to the Lutherans and Calvinists, who used the last? Was it to further separate themselves and reenforce this desire that was later referred to as "Radical Reformation?"
This is wrong. The Amish used the last name of Jakob Ammann, the founder. Memmonites used the first name of Menno Simons, likely because it was more distinctive.