What's the story behind the construction of Dixit Wada? Who initiated it and when was the foundation laid?

The idea for Dixit Wada was initiated by Kakasaheb Dixit himself after his second visit to Shirdi in December 1909. As Chapter 4 describes, his initial thought was modest: to build a tin roof for the convenience of pilgrims. However, this idea soon evolved into a firm decision to construct a proper stone Wada. The foundation stone was laid the following year, in 1910. The foundation work was completed on December 9th after receiving Baba's approval, and Baba gave the final order for Dixit to lay the foundation on December 10, 1910.