One of the Maimonides' 13 principals is the belief in resurrection of the dead but what is the qualifier for this? Does this only include Jews? Does it only apply to the righteous? Will Noachides rise again? Could evil Jews or evil gentiles that performed t'shuvah before death rise again? Sources?
To answer your question fully we first have to define our terms.
What is resurrection
In his work called Chelek, Maimonides clearly indicates that the intellect (the nefesh) goes to the world to come and joins the higher intellect. That is to say that there is no physical resurrection, only spiritual. The Shem Tov ben Yosef Shem Tom captures his thinking. He writes that he [Maimondies] “did not believe in a physical resurrection.” In the Mishneh Torah, he confirms this when he writes:
“In the hereafter neither a body nor a body shape exists, but the souls of the righteous without bodies.”
Classical Judaism and Talmud(s) state that after the arrival of the messiah, a period will be followed by resurrection. However, many modern scholars now feel that this notion was brought into Judaism from pagan Zoroastrianism and Babylon. Like the names of the months which the rabbi honestly admit came from Babylonian gods. The closest hint to a bodily resurrection in the Bible can be found in Daniel 12 which is debatable. If we take the latter approach and say that resurrection is a spiritual endeavor then the only difference in the messianic age (olam haba) is that Jews will live in Israel and not be submerged under foreign rule nor will they be subject to enslavement by other nations. Although he does not deny a physical resurrection in his treatise, it has been noted by some scholars who doubt whether he ever wrote the Treatise on Resurrection, however, that too is debatable.
Do only Jews go to heaven?
Many traditional Jews feel that only Jews or only righteous Jews living in Israel will resurrect. The political message is obvious: come to Israel. It is also possible that the persecutions by non-Jews would prompt any rational Jew, understandably, to say that non-Jews have no share in the world to come and hence do not get resurrected at all. For example, the Spanish poet, Yehudah Halevi was convinced that Jews are biologically superior to non-Jews. Even Noahides or converts do not meet the criteria of a Jew. They are little better than animals. Addionaonly, Adam, Abraham, Jacob were non-Jews who we'd expect would resurrect.
Contrary to this racist opinion was Maimonides who believed in universalism. Maimonides was proud to be an observant Jew. He was also proud of the Jewish people yet, he did not think Jews were superior and that this was innate, instilled into the Jewish people. He felt that Jews were no better than other people, save the obeisance of the Torah, respectfully. This being the only distinction of the Jew. But anyone could convert and indeed this would take place in the messianic age. Ruth was a gentile who converted and Kings David and Solomon, as well as the Messiah, will descend from her. We see from here that gentiles have the same capacity to become the greatest leaders as those who are born to Jewish parents.
In short, Everyone is created b’tzelem Elohim, “in the image of G-d." Maimonides defines this image to mean intelligence, hence it is a duty to use one's intellect because that is the closest thing to G-d and it is the thing that separates us from animals.
 Commentary to Mishnah, introduction to Perek Chelek and Mishneh Torah, Hilkhot Teshuvah 8.
 For support of this view see Rabbi Moshe Ben-Chaim's article in the Jewish Times "Jews: A super Race?".
 For more information please see Menachem Keller who stresses this point in his book Maimonides on Judaism and the Jewish people, and again in his article “Chosenness. Not Chauvinism: Maimonides on the Chosen People”