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Isn't the friction dependent upon the normal force which on Mars would be less. Therefore, shouldn't the force required to overcome that also be less?

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Absolutely, if you were pushing a block along the ground. Fortunately modern "wheel" technology reduces the bearing friction so much that it is no longer a factor. The only friction left is the friction holding the wheel to the ground. This is reduced in reduced gravity, such that wheels are more likely to slip.

Wheels need friction to develop acceleration. So its a negative not a positive.

It's only a negative if the vehicle needs to accelerate quickly. So sufficient friction is sufficient, not a negative or a positive.

Given that the batteries store roughly 2.4 kW-h, it's probably safe to assume that the max drive power is less than 500 watts (2.4 kW-h / 10 hours -> 240 watts). Earth side electric vehicles commonly have drive power over 100 kilowatts.

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