With increasing direct current (DC) deployments in distribution feeders, microgrids, smart buildings, and highvoltage transmission, there is a need for better understanding the landscape of power flow (PF) solutions and for efficient PF solvers with performance guarantees. This work puts forth three approaches with complementary strengths towards coping with the PF task in DC power systems. We consider a possibly meshed network hosting ZIP loads and constant-voltage/power generators. The first approach relies on a monotone mapping. In the absence of constant-power generation, the related iterates converge to the high-voltage PF solution, if one exists. To handle distributed renewable generators typically operating in constantpower mode, an alternative Z-bus method is studied. For bounded constant-power generation and demand, the analysis establishes the existence and uniqueness of a PF solution within a predefined ball. Moreover, the Z-bus updates converge to this solution. Third, an energy function minimization approach shows that under limited constant-power demand, all PF solutions are locally stable. The derived conditions can be readily checked without knowing the system state. The applicability of the conditions and the performance of the iterative schemes are numerically validated on a radial distribution feeder and two meshed transmission systems under varying loading conditions.