bikkurim -- not just thanks to G-d; why no nechama in this tochacha; choser kol - not if you have a gemara!

1) The Maor v'Shemesh has a striking hesber of the mitzvah of bikkurim that emphasizes the chassidic idea of connecting with the tzadik. At first glance, the mitzvah of bikkurim is about giving thanks.  However, if that's all there is to the mitzvah, then why travel all the way to the Beis haMikdash with a gift of new fruit for kohen? You can give thanks to Hashem at home. Maor vaShemesh therefore suggests that the idea of bringing bikkurim is to connect oneself to the kohen, to the tzadik, to someone on a higher level of avodah, and through that connection to elevate oneself. To quote a taste:

וזהו שפירש"י ז"ל ובאת אל הכהן וכו' ואמרת אליו הגדתי היום וכו' שאינך כפוי טובה אין הפירוש שיצטרך להגיד שאינו כפוי טובה לנגד השם רק הפירוש הוא שאינו כפוי טובה לנגד הכהן ושמכיר שכל הטובה הוא באה לו ע"י המשכת הכהן וזהו שאמר הגדתי היום לה' אלהיך ויחד שמו יתברך על הכהן דייקא להורות מה שאמרנו שמחזיק טובה אל הכהן שע"י ההשפעה שהוא ממשיך בגודל יחודיו הוא אוכל בסבתו

Bikkurim is about hakaras ha'tov, but rather than address our thanks to G-d, Maor v'Shemesh says to address our thanks to the tzadik, as he is the one who enables our tefilos and avodah to do what they need to do.

He emphasizes the point again in the next piece: שענין הבכורים היתה להורות שלא בכוחו ועוצם ידו הוא עושה חיל רק שהברכה באה לו על המשכת השפע שמושכין הצדיקים ע"י ייחודיהם

The next parsha in our sedra deals with viduy maasros. Why is it called viduy? We are not confessing to some crime? Seforno answers that had we not sinned in the cheit ha'eigel then avodah and all the gifts that go with it would belong to the bechorim. When we give away tru"m to the kohanim, we are acknowledging the sin of the eigel that forced us into this position.

The Shem m'Shmuel (5672) offers a different hesber:

ולפי האמור יתפרש בטוב הענין וידוי מעשר שמתודה שמצד עצמינו אין אנו ראויים לדיבוק אלקי ואנו נזקקים לאמצעות הכהנים והלוים ועניים ועדת החסידים כנ"ל:

This piggybacks on the Maor v'Shemesh's idea that we need the help of a kohen/rebbe/rabbi to help us find our way, and bikkurim, terumos, maasros, etc. forges a connection to these people. It's called viduy because of that recognition that we can't get there ourselves. We are acknowledging our limitations, our shortcomings, even as we struggle to reach out and find a way to transcend them.

I'm not so much of a chassid, but I think we can take something away from this idea anyway. When a person is blessed with their bikkurim, with their first taste of success, the reflex of a religious person is to turn to G-d and thank Him. It's purely a bein adam l'Kono interaction. We know our success does not belong to us alone, but comes through siyata d'Shemaya. What our parsha is perhaps telling us is to extend that thanks outward to the world of bein adam l'chaveiro as well. Not because your friend or neighbor directly helped you complete your PhD or close the big deal or put in a good word so that you got that promotion -- that probably was not the case. But do you really think it was entirely your bein adam l'Kono that got you all that? Are your prayers so powerful and effective that they merited Hashem giving you what you asked for? Are your zechuyos so great that they were enough to bring Hashem's blessing? Maybe you got what you wanted because you are part of a community that deserves siyata d'Shemaya.

If it was just about you, then you could stay home, eat your bikkurim, and say a bracha on them to thank G-d. But that's not enough. You have to recognize that you are part of a community, part of a nation, and your success is a product of their tefilos and avodah as much if not more than your own. Therefore, the mitzvah requires that you travel to Yerushalayim, that you connect with the kohen, with the levi, with others who are engaged in avodah which indirectly benefits you as much as themselves.

2) תַּ֗חַת אֲשֶׁ֤ר לֹא־עָבַ֙דְתָּ֙ אֶת ה׳ אֱלֹקיךָ בְּשִׂמְחָ֖ה וּבְט֣וּב לֵבָ֑ב מֵרֹ֖ב כֹּֽל׃

וְעָבַדְתָּ֣ אֶת־אֹיְבֶ֗יךָ אֲשֶׁ֨ר יְשַׁלְּחֶ֤נּוּ יְהֹוָה֙ בָּ֔ךְ בְּרָעָ֧ב וּבְצָמָ֛א וּבְעֵירֹ֖ם וּבְחֹ֣סֶר כֹּ֑ל וְנָתַ֞ן עֹ֤ל בַּרְזֶל֙ עַל־צַוָּארֶ֔ךָ עַ֥ד הִשְׁמִיד֖וֹ אֹתָֽךְ׃ (Devarim 28:47-48)

R' Gershom Eidelstein found a Mechilta (HaChodesh 1:9) that interprets as follows:

. דָּבָר אַחֵר: "וּבְחֹסֶר כֹּל", שֶׁיְּהוּ חֲסֵרִין תַּלְמוּד תּוֹרָה וּמָמוֹן וְדֵעָה וְחָכְמָה וּבִינָה. דָּבָר אַחֵר: "וּבְחֹסֶר כֹּל", שֶׁנִּטְּלָה מֵהֶן הַדַּעַת.

Mashma that you can be in a state of בְּרָעָ֧ב וּבְצָמָ֛א וּבְעֵירֹ֖ם, but if you still have דַּעַת (R' Gershom said so long as you still have talmud Torah, but that pshat in the midrash lists מָמוֹן alongside t"T, so I am not sure limud really stands on its own) things will not be as bad. See Viktor Frankl's book for an exposition on this point.

The flipside is no less true. תַּ֗חַת אֲשֶׁ֤ר לֹא־עָבַ֙דְתָּ֙ אֶת ה׳ אֱלֹקיךָ בְּשִׂמְחָ֖ה וּבְט֣וּב לֵבָ֑ב מֵרֹ֖ב כֹּֽל׃׃ַַ֗֗ means you have רֹ֖ב כֹּֽל, you have learning, you have da'as, you are sitting in front of a gemara all day, but you are not filled with simcha, then that's the cause for tochacha. If you weren't "shivti b'beis Hashem" and parked in front of a gemara, neicha that you feel dissatisfied, but if you are blessed to be able to sit and learn, even if you are lacking in the luxuries of life, you should still feel fulfilled.

3) Shu"T Radbaz (2:769) asks why we don't find any pesukei nechama at the end of the tochacha in Ki Tavo like we do in the earlier tochacha in Bechukosai. He gives three answers: 

A) גַּ֤ם כׇּל־חֳלִי֙ וְכׇל־מַכָּ֔ה אֲשֶׁר֙ לֹ֣א כָת֔וּב בְּסֵ֖פֶר הַתּוֹרָ֣ה הַזֹּ֑את יַעְלֵ֤ם ה׳ עָלֶ֔יךָ עַ֖ד הִשָּׁמְדָֽךְ׃ although Rashi interprets יעלם – לשון עלייה, the Zohar interprets it as העלמה, i.e. Hashem will turn aside and ignore the punishments that might be deserved. As Radbaz notes, the pshat is certainly like Rashi, but at least derech remez, we see that behind the scenes there is something positive going on.

B) It is the shem Havaya, the shem of rachamim, that appears throughout the tochacha. The fact that everything done is b'hashgachas Hashem and for our benefit in the nechama.

C) The bris of the tochacha concludes not in our parsha, but continues in Netzavim. It is there that the pesukei nechama which conclude the discussion of the bris appear.

There is a takana to read the tochacha at the end of the year, tachel shana v'kililoseha. We never actually conclude the year with Ki Tavo, but always have Nitzvavim/Vayelech separating it from Rosh haShana. This makes perfect sense according to this final reason, as Nitzavim is really the concluding section of the bris in Ki Tavo.