Abstract: The formation histories of massive disk galaxies are key to understanding galactic hierarchical assembly and matter distributions. Within the Local Group, Andromeda (M31) provides a unique opportunity for detailed reconstructions of galaxy formation history, where its active merger history sets it apart from the Milky Way (MW). Two primary outstanding questions remain concerning M31's assembly history:  has its disk survived a major merger within the last few billion years, and does this major merger coincide with the formation of M31's Giant Stellar Stream (GSS) and its various tidal shells? In this talk, I will present results from the Elemental Abundances in M31 and Spectroscopic and Photometric Landscape of Andromeda's Stellar Halo (SPLASH) surveys on resolved stellar chemodynamics in M31's disk region and GSS-related tidal substructure. I will discuss implications for the formation of M31's disk and inner stellar halo and constraints on the nature of M31's last significant merger.  I will conclude by highlighting the utility of modern spectroscopic studies of resolved stellar populations in M31 for connecting our MW-based understanding of galaxy formation to future observations of disk galaxies in the Local Volume.