I read somewhere that the bigger the surface area for the redox reductions to take place, and ultimately, the more redox reactions that take place, the more electrons that flow through an external circuit and the more electricity that can be generated. If this is the case, what does the voltage of a fuel cell, which I believe is caused by using dissimilar metals for the electrode and anode (correct me if im wrong) has to due with the amount of electricity and electrons generated? doesn't V=IR tell us that for some fixed Voltage we will get some fixed current if resistance is kept constant.
The electrode materials and the fuel determines the cell voltage.
No current will flow from the cell without an external resistance connected. As the resistance is decreased, the current drawn increases, up to a limit set by the surface area of the electrodes or the amount of fuel being supplied, whichever bites first.
Increasing the limiting parameter, surface area or fuel supply, will increase the limit on the amount of current that can be drawn from the cell.