Over the past two decades, coalbed methane (CBM) has become one of the major unconventional gas resources in the US, Canada, Australia, and other countries. Despite substantial advances in CBM exploitation technologies, there is still a need for an accurate characterization/quantification and implementation of the gas-diffusion behavior, gas contents, moisture content and influence, and methane banking. Unlike what once was widely assumed, the value of the gas-diffusion coefficient is not constant over the life of a CBM reservoir. In low-rank coal reservoirs, the free and soluble gas contents cannot be considered negligible compared to the adsorbed gas content and they need to be quantified. Coal moisture impact on the sorption isotherms and processes needs to be identified. Through a comprehensive characterization, modeling, and integrated simulation study of the coalbed methane of the Big George Coal, Wyoming, this study investigates implications of variable diffusion coefficients; quantifies the free, soluble, and adsorbed gas contents to examine their contributions to the total gas production; and examines the impact of the moisture content on CH4 and CO2 sorption isotherms and CBM recovery processes. This study incorporates the impact of the pressure and temperature on coal adsorption capacity variation. Additionally, the effects of coalbed water properties - salinity, density, and methane solubility - were explored. There is a negative correlation between diffusion coefficient and pressure at low pressures. Since the pressure in Big George Coal is relatively low, this study investigates the impact of having a varying diffusion coefficient on gas production. For low permeabilities, the assumption that methane production is permeability-controlled may be accurate, but for high permeabilities, variable diffusion coefficients can have a significant impact on methane production. Amongst many aspects, this study explored an accurate estimation of the free, soluble, and adsorbed gas contents, and diligently accounted for methane and CO2 solubilities in water. In the case of undersaturated coal and during ECBM, the injection of CO2-rich gas leads to methane banking. Furthermore, the impact of anisotropy and heterogeneity on gas flow was analyzed in terms of diffusion, adsorption, and permeability. A moderate increase in the diffusion coefficients significantly impacts the gas production rates. This should, particularly, be considered for CBM reservoirs with high permeabilities or when considering enhancing low-permeability CBM reservoirs through hydraulic fracturing. The free and soluble gas contents in low-rank coal should not be ignored, and an estimation of their values is provided. The coal moisture content has a significant impact on the sorption isotherms and gas production rates. Future work should include monitoring methane banking and using this consideration in the planning of optimum well spacings.