[schoen]

Yes, you can add more axioms and produce a more powerful system which can resolve more questions. In some cases you actually have a choice about whether to assume that something is true or that it's false (for example you can assume the continuum hypothesis or its negation!), and neither choice on its own produces an inconsistency, but either choice makes a different set of conclusions provable.

However, Gödel made explicit in the very first statement of his incompleteness theorem that assuming more axioms cannot ever eliminate incompleteness (except by the extremely undesirable event of eliminating consistency). Gödel shows that, if a set of axioms (including additional axioms on top of your original set) doesn't allow you to prove everything (by virtue of being inconsistent, something called the "principle of explosion"), then there are necessarily statements that those axioms can't resolve the truth of.

So you can add more axioms and that will either make your system more powerful or inconsistent (depending on whether you chose inconsistent axioms to add), but you still can't get rid of the incompleteness phenomenon that way!