1. Rav Chaim Falagi's pirush on Tehillim, in 33:14: מִמְּכוֹן שִׁבְתּוֹ הִשְׁגִּיחַ אֶל כָּליֹשְׁבֵי הָאָרֶץ. notes that the first letters of the first three words are משה, and the last three are נוח, or, if you prefer, ונח. He says that Moshe was a gilgul of Noach's neshama. The Arizal says the same thing. They both note that Noach and Moshe were saved by being placed in a Teiva, which was floated upon the medium that brought death to the others of their generation- Noach the waters of the Mabul, which killed everyone of his generation, and Moshe the waters of the Nile, into which his cohort of male children had been thrown to drown. This neshama, Noach's, was given the opportunity to do its mitzva a second time, this time doing it properly. Although Noach was a great Tzadik and beloved by Hashem, he was criticised for not doing enough to influence and save the people of his time. Moshe rectified this failure, because when Klal Yisrael did the sin of the Eigel, and Hashem told him that the people deserved destruction, and that Moshe would be the only survivor who would begin a new race, Moshe did not accept this terrible gzeira. Moshe said that he cannot exist without the people he was responsible for. He said, Hashem, forgive the people, and if not, מחני נא, erase me from your book of life. The words מחני נא are an anagram for מנח אני. Hashem, this is my second chance. This time, I cannot live if my people die. If they die, I will die with them. (This idea is brought in many places: for example, it is in the Yalkut Reuveni in the beginning of Tetzaveh quoting the מגלה עמוקות, and in the Chasam Sofer's Drush for zayin Adar in 91)
I know less than nothing about gilgulim. What I see in this story is that שכר מצוה מצוה, and the schar of a mitzva done imperfectly is the the opportunity to try to do it better. מצוה גוררת מצוה, and it can be gorer the ability to perfect it.
2. Bava Kama 92b-
א"ל רבא לרבה בר מרי מנא הא מילתא דאמרי אינשי מטייל ואזיל דיקלא בישא גבי קינא דשרכי אמר ליה דבר זה כתוב בתורה שנוי בנביאים ומשולש בכתובים ותנן במתניתין ותנינא בברייתא כתוב בתורה דכתיב (בראשית כח) וילך עשו אל ישמעאל שנוי בנביאים דכתיב (שופטים יא) ויתלקטו אל יפתח אנשים רקים ויהיו עמו ומשולש בכתובים דכתיב [בן סירא יג] כל עוף למינו ישכון ובני אדם לדומה לו תנן במתני' כל המחובר לטמא טמא כל המחובר לטהור טהור ותנינא בברייתא רבי אליעזר אומר לא לחנם הלך זרזיר אצל עורב אלא מפני שהוא מינו
The Bechor Shor there in BK, in the path of the Arizal, discusses the harmonious association of the Yona with Noach, in contradistinction to the dissonant relationship with the Raven, says that עופות טהורות, clean-species birds, are often to be found in the vicinity of Tzadikim. He says that they are souls that need a little elevation, and when the tzadik shechts them and does כיסוי הדם, and uses them to enable him to live and do mitzvos, this lifts up their souls. Noach, too, kept mitzvos of the Torah, and this is why the dove was closely associated with him. (נשמתן של רשעים מגולגלים בעופות טמאים, ויש נשמות צדיקים אשר צריכים איזה תיקון ומגולגלים בעופות טהורים, וע״י שנשחטה שחיטה כשירה ומכסים דמה בברכה זהו יקונה, ולכן נ״ל דדירתן עם הצדיקים, שבאותן עופות כון רק מתכוץ לשכון עם הצדיקים, ומתרץ ההוא משוס ובן אדס לדומה לו, פי׳ הבן אדם המגולגל באותו עוף הוא המתקרב לדומה לו)
3. The first Rashi in the parsha, on 6:9: אלה תולדות נח נח איש צדיק: הואיל והזכירו ספר בשבחו, שנאמר (משלי י ז) זכר צדיק לברכה. דבר אחר ללמדך, שעיקר תולדותיהם של צדיקים מעשים טובים: (This is from the Tanchuma here, Noach 2.) These are the generations of Noah—Noah was a righteous man: Since Scripture mentions him, it tells his praise, as it is said (Prov. 10:7): “The mention of a righteous man is for a blessing.” - [Pesikta Rabbathi 12]. Another explanation [for why the names of the children are not mentioned immediately following “These are the generations of Noah”]: To teach you that the main generations [progeny] of the righteous are good deeds. What does this mean, that the main progeny of Tzadikim is their good deeds? No doubt, it is a homiletic device to convey the idea that children are the means by which we remain in the world even after we die, because we leave behind something important and lasting. For Tzadikim, their good deeds are so powerful that they change the world for the better, and so for them, their "progeny", the means by which they live after death because they continue to influence the world, is their good deeds.
But the Mahari Mintz, in his drashos, says that he once saw in a Zohar that based on this Rashi, the widow of a tzadik that died childless does not have the mitzva of Yibum. Yibum is only for a person that died ובן אין לו, without child, and a tzadik has children- his good deeds are his children. His good deeds are more than children. The fact that in halacha such a woman does do yibum is only on behalf of some other lost soul of a person who was not a tzadik who died childless. (Not to distract, but this Mahari Mintz mirrors the Mordechai about yibum for a Rasha. See here.)
To me, this means that mitzvos are like neshamos, again continuing the theme of the parsha. Mitzvos generate neshamos; neshamos are created by and through mitzvos; each one builds the other in a rising spiral of hashra'as hashechina.