1. which art movement was the biggest inspiration for conceptual art?

Dadaism! The most iconic piece of work from the dada movement is Marcel Duchamp's Fountain. It's literally a urinal with the signature R. Mutt on it! Duchamp's "found objects" is when he would take random, everyday objects, put them together, and call it art. Dadaism abolished previous notions of art being primarily visual and helped kickstart many postmodernist ideals.