Having taught us the Din of males making Aliyas ha'Regel (in Sh'mos 34:23), why does the Torah see fit to repeat it here?
Rashi: To teach us that even in the Sh'mitah year, (see Pasuk 11) the Regalim remain intact. 1
Sifsei Chachamim: Seeing as they are closely connected with the seasons Refer to 23:16:6:1, which basically do not apply during the Sh'mitah year. Rosh - the Havah Amina was that we are not concerned for the order of the festivals. (E.g. R. Shimon holds that Bal Te'acher is after the three festivals passed in order, starting from Pesach - Rosh Hashanah 4a. - PF)
What are the implications of the word "Yera'eh", which is written the same as 'Yir'eh' (in the form of a K'ri K'siv)?
Chagigah, 2a: It implies that, just as Hakadosh-Baruch-Hu comes to see you with two Eyes, so too, should come to se Him with two eyes, thereby exempting a person who is blind in one eye from the Mitzvah of Aliyas ha'Regel; 1 and just as Hakadosh-Baruch-Hu comes to see free of charge, so too, do you come to see Him free of charge
See Torah Temimah for references to other interpretations of this D'rashah.
What does "Kol Zechurcha" come to preclude?
Chagigah, 4a: "Z'chur" preludes women; Z'churcha", Tumtumim and Androginusim (who are Safek Z'charim) from the Mitzvah of Aliyas ha'Regel. Whereas "Kol" comes to preclude someone who collects dog-feces (for tanning skins), someone who smelts copper and a tanner
What are the implications of the words "ha'Adon Hashem"?
Chagigah, 4a: It confines the Mitzvah of Aliyas ha'Regel to someone whose only Master is Hashem, to preclude Avadim who have another master.
Yerushalmi Chagigah, 1:1: Together with the rest of the Pasuk it implies that whoever performs the Mitzvah of Re'iyah, it is considered as if he greeted the Shechinah.
Seforno: a. Since Hashem is the Master of all who come before Him, it is as if one is going to greet one's Master; b. Hashem is the Master of the land, 1 and one is obligeted to appear before Him on the Yamim-Tovim in order to thenk Him for the various stages of harvest