This work presents a series of investigations aimed at the quantitative prediction and active control of hot-electron preheating in laser-driven Inertial Confinement Fusion (ICF). First, a scaling model for the hot-electron fraction was established by analytically deriving nonlinear saturation processes from first principles. This model, grounded in "Resonant Density Interval" theory, has demonstrated robust cross-platform performance through validation against experimental data from multiple large-scale laser facilities. Second, the study elucidates the impact of multi-beam irradiation configurations on hot-electron angular distributions by analyzing the coupling mechanisms of two-plasmon decay (TPD) and stimulated Raman scattering (SRS) via shared electron plasma waves. Furthermore, to address the mitigation of hot electrons produced by laser plasma instabilities, the performance of broadband lasers has been evaluated through experiments on the Kunwu facility and integrated numerical simulations. We identified that instantaneous intensity modulation peaks are the primary drivers for the breakdown of broadband suppression, leading to the proposal of a spatiotemporal smoothing strategy via multi-beam superposition. Collectively, these findings provide a comprehensive predictive framework and refined physical insights into laser-plasma interactions, offering vital support for the design of future high-gain ICF experimental schemes.