I have no specific knowledge of the 146, having relinquished an assignment on the Type many years ago, so I must defer to the knowledge of those who do. However, I find it strange that a significant sideload is achieved during certification testing as the max aft cg consideration normally constrains what can be achieved. Learn something new each day, I guess ...
Aileron drag can be quite significant. A four-engined beastie of my past demonstrated a distinct preference for the grass unless appropriate full aileron was applied without delay ...
Re V1 and weight, minimum schedules will have V1 reducing with weight (until V1 becomes Vmcg-limited, at which stage the operationally permitted reduction ceases). If conditions and the AFM permit, however, one can then schedule an overspeed (or improved performance) takeoff with higher than minimum V1, VR, and V2.