In dense biofilm settings, the bacterium Myxococcus xanthus exhibits a remarkable repertoireof collective multi-cellular dynamics, including both rippling wave motion and aggregate formation, which are inducible by various experimental conditions. In this dissertation, we explore the emergence of such behavior within a collective continuous-time random walk model. The model describes the random locomotion of individual cells whose biased random navigation decisions are conditional upon external cues, i.e., signals, generated by the ambient cell population. The model is formulated in terms of a recently proposed integral equation (IE) formalism which directly provides particle and current densities that are already averaged over the entire space of all random trajectories, without requiring the generation of large random trajectory samples, in contrast to agent-based simulation approaches. Essential to our modeling approach is the incorporation of experimentally derived data bases of random trajectory components and their associated local cues generated by the ambient cell population. These data bases are the crucial input to construct the navigational Markov chain transition probability which defines our random walk model. Assuming strong nematic cell alignment, the model is reduced to one dimension (1D). Both total and partial, left- and right-moving cell densities are explored as possible external signals which bias the 1D cellular random walks, along the population's local nematic alignment axis. Two experimental data bases are examined as model inputs: a rippling data base (RDB), from a rippling experiment, and an aggregation data base (ADB), from an aggregation experiment. The model solutions are very sensitive to even small input parameter changes and exhibit a wide, diverse range of collective dynamical patterns, including multiple variants of both rippling and aggregation behaviors. The model results are qualitatively consistent with the underlying experiments, in that rippling is seen predominantly in RDB-derived model results, whereas aggregation is predominant in ADB-derived results. Consistent with experiments, examples of co-occurrence of both aggregation and rippling wave activity is found. Exotic, heretofore unobserved patterns are also reported, including a pattern we termed "anti-rippling", where local cell density depletions, rather than density accumulations, perform coordinated rippling-type wave motions.