Then add the largest load to this number to cover the starting surge, bringing the total requirement to 5100 watts. At the high end are the Hondas. At the low end are the Colemans. A good compromise of efficiency, noise, and features are the Generacs. Best price is at Home Depot.
Wheels are extra.
Two ways, either install a big switch upstream of your main breaker, or install a sub-panel with a dual interlocked feed. To install it, simply move your critical circuits from the main panel to the sub-panel. The sub-panel is fed from both the main panel and the generator. The breakers from these two sources are interlocked to prevent back feeding.