Alkaline CO2 electrolyzers hold promise for sustainable chemicals and fuels; however, durability challenges, particularly carbonate salt precipitation, hinder their widespread adoption. This study investigates the water and ion transport properties of anion exchange membranes (AEMs) in zero-gap membrane electrode assembly (MEA) configurations, moving beyond the traditional water uptake measurements used in previous CO2 electroreduction literature. The water and potassium transport properties of the three widely used commercial AEMs - PiperION (Versogen), FAA-3 (Fumatech), and Sustainion X37-50RT (Dioxide Materials) - were systematically evaluated using metrics such as water diffusion, transport number, permeability, potassium diffusion, and transference number. Chronopotentiometry was used to identify a critical current density beyond which drying or salt precipitation leads to system failures. Operating at current densities 25% lower than the critical current density significantly extends continuous DC operation from approximately 50 hours to at least 500 hours. Water diffusion and permeability were measured in a liquid-gas cell as a function of membrane thickness. Results indicated Sustainion X37-50RT had the highest water diffusion (3.2 x 10-6 cm2 s-1), followed by PiperION (7.9 x 10-7 cm2 s-1) and FAA-3 (2.9 x 10-7 cm2 s-1). This same trend was observed for water permeation and transport number measurements. Potassium diffusion and transference numbers were measured using a liquid-liquid cell with 0.1M NaHCO3, and 0.1M KHCO3 on each side. Sustainion X37-50RT membranes have the highest potassium diffusion coefficient (6.5 x 10-7 cm2 s-1), followed by FAA-3 (6.0 x 10-8 cm2 s-1) and PiperION (4.5 x 10-8 cm2 s-1). Potassium transference numbers were measured across current densities ranging from 0 to 100 mA cm-2 and held the same trend as the potassium diffusion coefficients. Critical current densities followed the same trend as water diffusion with Sustainion X37-50RT having the highest (180 mA cm-2), followed by PiperION (45 mA cm-2) and FAA-3 (30 mA cm-2). This trend indicates water diffusion to the cathode is crucial to preventing carbonate salt precipitation, especially at increasing current densities. These findings provide fundamental insights for advancing industrial-scale CO2 electrolysis.