Sorry if this is a dumb question! Superman was born on Krypton, but raised on Earth and therefore just barely exposed to his home planet. Would someone who lived their entire life on Krypton and then came to Earth be stronger than Superman?

Superman get's his powers from Earth's yellow sun while Krypton has a red sun that negates his powers. So since Superman has been on Earth all his life absorbing yellow sun radiation he should be stronger than any other Kryptonian.

Well, saying that Kryptonians get their powers only from yellow sunlight is a serious oversimplification, but for now lets use it. In comics generally accepted concept that “the longer kryptonian remains under yellow sun, then stronger s/he gets”. Following this logic, Superman, living on Earth since early childhood, has more both raw power and experience in using his abilities than others of his race.

Not a dumb question at all. There's no dumb questions when someone has real questions.

This being said... Kryptonians don't get their powers from the immense gravity of the planet, it has something to do with Krypton's geology. There's something unique about it (kryptonite being an example of it). In the pre-flashpoint timeline Doom Patrol leader The Chief, got his hands on a live kryptonian from New Krypton and did live experiments on the poor guy. After studying kryptonian physiology, he came to the conclusion that kryptonians don't get their powers because of the presence of some kind of special organ, or because their DNA is more extensive than ours, but because kryptonian bodies possessed unique atoms in their atomic structure.

But if we choose to forget this piece of information DC gave us we can use simple logic to simply come to the conclusion that even if Superman was able to absorve all the light arriving at Earth it still would not be enough to explain his power levels. So logic dictates (even comic book logic) that the powers of a kryptonian are not entirelly powered by the sun, but they most obtain more than 90% of their energy from another source.

Basically this says that sunlight from stars above M class, act more like a catalyst than a power source, adding to kryptonian physiology a kind of initial charge that allows their bodies to tap into other types of energy. A little like what happens to Cyclops from Marvel. His body also absorves sunlight, but his powers are not powered by sunlight, but rather some sort of extra-dimensional energy, sunlight just serves to make him able to tap into that energy. So, the same logic could be applied to kryptonians, where different and more powerful types of sunlight gives a kryptonian access to immense amounts of energy, that in turn is processed and used in a specific manner.

Or you can go with the cliche explanation and say "Kryptonians have powers just because."