When writing a paper, I feel like to point out exact references to the following seemly easy facts concerning flat structures on a closed surface $\Sigma$ with negative Euler characteristic: 1. Any flat metric with conic singularity on $\Sigma$ is quasi-isometric to a hyperbolic metric. 2. Define two flat metrics $g_1$ and $g_2$ by means of holomorphic $n$-differentials $U_1$ and $U_2$. Then $g_1$ and $g_2$ are quasi-isometric and the ratio of quasi-isometry can be controlled by $\|U_1-U_2\|$. Please either give me a reference or a simple proof/explanation. Any help is appreciated!