Using multiscale modeling approaches ranging from first-principles calculations within density functional theory and nonequilibrium rate equation approaches, we elucidate the atomistic growth mechanisms of graphene on several stepped transition metal substrates. Our studies (a) reveal why Cu substrates are highly preferred to catalyze mass production of quality graphene, (b) identify a novel kinetic pathway towards effective suppression of undesirable grain boundaries in graphene growth on Cu(111) via chemical vapor deposition, and (c) propose the use of aromatic molecules as carbon sources for graphene growth at dramatically reduced growth temperature. We also explore the possibility of establishing long-range ferromagnetic order in graphene via a novel compensated n-p codoping approach. The main findings will be discussed in close comparison with experiments.