1.) Yes. Larger root mass, Larger plant.. the longer it takes to get those nutes from the roots to the top of the plant.
2.)No. Kinda what Opie said, it's genetics.. however, you can get more dense and thicker bud off a smaller plant.. not always, but can.

Maximize what you yield from one seed by cloning. Clones can be rooted under any light cycle... they just require super high humidity. You can cut, root and veg all in the same area as your mothers.. than when ready put those clones into flower...

Hope this helps.
Bob.