Do I need to seal coat part of my new asphalt?
Asphalt doesn't crack due to porosity. It cracks when it expands and contracts due to heat cycles, and as it dries out from age. Poor substrates exacerbate this. 

Once they are cracked freezing water has much more of an effect. Then it's able to push with enough force to cause damage. 

Sealers mostly preserve the surface appearance. They don't do much at all to increase longevity. 

The point is, unless you want to keep the surface visually uniform, I wouldn't worry 'bout it. I'm sure others would.