1) i) The Maharam Ibn Chaviv answers this question based on a Mishnah (Bikkurim 3:1) that teaches that as soon as a farmer observes that his fruits have begun to grow, he immediately ties a string on them and legally declares that they are bikkurim. The Yerushalmi (Bikkurim 10b) adds that this may be done even while the fruits are still small and unripe. Because the halachah is (Orach Chaim 202:2) that a person who eats a unripe grape recites the blessing, the Torah therefore describes this mitzvah as taking the first fruits of the land.
ii) Alternatively, the Chida explains that the phrase does not refer to the fruits, which as noted would more correctly be described as fruits of the tree. Rather, it teaches us that an integral component of the mitzvah of bikkurim is showing appreciation to Hashem for the land of Eretz Yisrael, as the farmer declares (Devarim 26:10) when he brings the fruits to the Beis HaMikdash: "And now, behold, I have brought the first fruit of the ground that You (Hashem) have given me."
iii) More recently, Rav Eliezer Waldenberg (Shu”t Tzitz Eliezer 15:16) used this linguistic anomaly as support for a tremendous chiddush [novel thought]. He discusses whether the mitzvah of bikkurim is an annual mitzvah that a farmer must do with the first fruits of each year’s produce, or is it a mitzvah he does once in his lifetime to thank Hashem for his land, at which point he is exempt from doing it again unless he acquires another field in the future? Since most people take it for granted that bikkurim is a yearly mitzvah, it sounds surprising to entertain the other possibility. However, Rav Waldenberg, who was renowned for his encyclopedic knowledge, writes that there is no explicit source in Chazal saying that bikkurim must be brought each year, and from the fact that they do not refer to it as an annual mitzvah, we may deduce that a farmer only needs to bring bikkurim once.
The Tzitz Eliezer suggests that this chiddush is rooted in a pasuk, as the Torah says, "You shall take from the first of every fruit of the land." Even though it would have been more accurate to write "from the first of every fruit of the tree," had the Torah done so, we would make the mistake of thinking that the mitzvah of bikkurim is incumbent upon each tree and must be brought annually. To prevent us from reaching this erroneous conclusion, the Torah went out of its way to refer to "the first fruits of the land" to teach us that the mitzvah is connected to the land, and once a farmer has brought bikkurim from a field, that field becomes exempt for the rest of his life.
2) Perhaps we can answer this question based on the chiddush of the Shu”t Chavas Yair (178). The Chavas Yair writes that with birds one can fulfill the mitzvah of simchas Yom Tov slightly, his reasoning is: "Because in important feasts they also serve birds." Therefore, although one doesn’t fulfill the main obligation of simchas Yom Tov with birds, a bit of the mitzvah he does fulfill.
Based on this chiddush, we can understand the Rabbeinu Bechayeh. Since birds brings at least a partial simcha, perhaps that’s enough to fulfill simchas Yom Tov. (Madanay Asher)
3) The Shu”t Avnei Nezer (Yoreh Deah 454, and 455) writes: "The main fulfillment of the mitzvah of Yishuv Eretz Yisrael is to have a job and be sustained from Eretz Yisroel. If one gets money sent from Chutz La’aretz, it appears to me that this is not a proper fulfillment of the mitzvah of Yishuv Eretz Yisroel. However, there is certainly still some fulfillment of the mitzvah of Yishuv Eretz Yisrael."
The Gilyonei HaShas (Kesubos 110b) writes: "I heard from an adam gadol that if one doesn’t get his income from Eretz Yisrael, he doesn’t fulfill the mitzvah of Yishuv Eretz Yisrael fully." Presumably, he is referring to the Avnei Nezer.
However, the Shu”t Minchas Elozor (5:12) writes: "I am in great shock, and everyone knows the great efforts that the holy sages, the rishonim who were like malochim – the Beis Yosef and Bach, would do to make sure that any money donated in Chutz La’aretz would go to Eretz Yisrael to help out the poor people who would be sitting and learning Torah in Eretz Yisroel. If so, we can’t believe that these strange words left the mouth or the quill of the holy Avnei Nezer, and certainly he never said such a thing, and certainly he didn’t write such a thing."
4) i) The Kadmonim (Rabbeinu Bechayeh, Shlach) bring that on a mitzvah which seichel [logic] dictates that one should fulfill there is no berachah, as the text of a berachah is "who has commanded us," which means we perform the mitzvah because Hashem commanded us, if we would do it anyway because of seichel, then we are not doing it because we were commanded to, therefore, we don’t make a berachah. We find by the non-Jews that they fight in order to live in their homeland, therefore, Jews as well should naturally do all they can to live in their homeland, and seichel dictates that a Yid should want to live in Eretz Yisrael. Therefore, there is no berachah on this mitzvah. (Shu”t Toras Yerucham, siman 9)
ii) The Rishonim write that the mitzvah of Yishuv Eretz Yisrael is not a mitzvah in and of itself, rather, it’s a mitzvah because it helps one be able to fulfill the obligation of separating terumas and maasros which are only obligated on a de’O’ raisa level in Eretz Yisrael.
The Ramban (Sefer HaMitzvos, Shoresh 12) writes that we don’t make a berachah when giving terumas and maasros to the kohen, as the main mitzvah is to separate terumas and maasros, and part of this is to give it to the kohen. Since, however, the giving to the kohen is not the main mitzvah in and of itself, there is no berachah.
Along the same lines, we can say, that Yishuv Eretz Yisrael is not the main mitzvah, it’s just that living in Eretz Yisrael allows one to separate terumas and maasros etc. Since it’s not the main mitzvah, there is no berachah. (Shu”t Pri Yehoshua, siman 66)
iii) In Birchas Hamazon we say: "We thank You, Hashem our G-d, for having granted as a heritage to our ancestors a desirable, good and spacious land & For all this, Hashem our G-d, we thank and bless You etc. as it is written: 'You will eat and be satisfied, then you shall bless Hashem your G-d for the good land He has given you.' Blessed are You, Hashem, for the land and for the food."
Included in these berachos is a berachah on Yishuv Eretz Yisrael. It is fitting that those who live in Eretz Yisrael should have kavonah when reciting this berachah, that it should also serve as a berachah on the mitzvah of Yishuv Eretz Yisrael. (Toldos Zev on Shabbos, Vol. 2, pg. 65)
5) Rav Chaim Kanievsky zt”l (Taima D’Kra) suggests that this anomaly alludes to one of the instructions left by Rav Yehuda HaChossid in his will, namely that nobody should wear the shoes of a person who has died. The pasuk mentions the word "garments" in the plural because after someone died, they were worn and used by other people, whereas the word "shoe" is in the singular because they were used only once.
