Abstract: Type Ia supernovae play a central role in both the discovery of cosmic acceleration and the measurement of the Hubble constant. In this talk, I will discuss two recent results that test the robustness of these foundations. First, I will show that recent claims of strong progenitor-age evolution undermining supernova cosmology are not supported by current data once standard environmental corrections are applied. Second, I will present the Local Distance Network, a community-driven, covariance-weighted consensus measurement of the local Hubble constant at 1% precision, confirming a significant tension with early-Universe predictions.