Leaky timing cover will have zero effect on fuel consumption.
I think the replacement is made extra difficult because you need to remove the crank pulley. the crank is not cut for a woodruff key for the timing sprocket, it is held in place by the friction washers and the clamping force of the crank pulley. So I think it is necessary to use the TDC tool to locate the crank, the cam holder tool to make sure the cam timing doesn't change, and replace the friction washers. Basically 90% of the job of replacing the timing chain.