Wire Laser Additive Manufacturing (WLAM) combines a wire feedstock with a laser heat source, offering high deposition rates and cost-effective material usage for welding and additive manufacturing. Traditionally, the wire is fed laterally into the melt pool, which imposes geometric constraints. To overcome these limitations, researchers have explored alternative laser and wire configurations. A recent advancement introduces the filler wire coaxially with a multi-beam laser system that symmetrically distributes energy around the wire, enabling the fabrication of complex geometries, particularly along curved trajectories. This configuration also offers significant advantages regarding bead dilution and microstructure development. However, process parameter control remains challenging due to the intricate energy distribution, affecting temperature fields, fluid dynamics, and microstructure evolution during solidification. To address these challenges, a finite element (FE) model within a level-set framework, incorporating periodic adaptive remeshing, is developed to simulate heat transfer and fluid flow in WLAM. Coupled with a cellular automaton (CA) approach, the model predicts microstructure formation, by epitaxial grain growth, based on the temperature field evolution. Instead of explicitly modeling the feeding wire, this latter is represented by a volume source domain within the melt pool, where an imposed velocity field simulates mass transfer effects. This study examines the influence of process parameters, including laser head rotation, from single- to multi-pass depositions using IN718 filler wire, on temperature field, melt pool evolution and final microstructure as well as part morphology. The model is validated through comparison with experimental IN718 deposits on matching substrates.