MISHNAH: LATE NETILAS LULAV
One who arrived from his travels where he did not have Lulav and Esrog must do Netilas Lulav upon entering his home, "upon" (meaning prior to) eating.
One who did not do Netilas Lulav in the morning may do so all day.
INTERRUPTING A MEAL FOR A PASSING MITZVAH
Question: While our Mishnah implies that he must interrupt his meal, we find regarding Tefilas Minchah that he may complete his meal!?
Answer (R. Safra): He must interrupt only when there is not likely to be sufficient time after his meal.
Question (Rava): Perhaps the distinction is simply between a d'Oraisa (Lulav on the first day) and a d'Rabanan (Tefilah)!?
Answer (Rava): Rather, R. Safra answered the following question:
Question: The Reisha implies that he must interrupt and the Seifa states that he has all day to make up the Netilas Lulav!?
Answer: In response to that question R. Safra distinguished between a case where he had sufficient time and where he did not.
Question (R. Zeira): Perhaps it is simply a case of l'Chatchilah and b'Di'eved!?
Answer (R. Zeira): R. Safra answered the first question (the difference between Lulav and Tefilah).
They are both d'Rabanan since we are speaking of the second day of Yom Tov, not the first.
This seems reasonable, given that the Mishnah speaks of one who is coming in from his travels.
MISHNAH: READING THE HALEL
One may have an Eved, Isha or Katan dictate the words of Halel for him to repeat, but cursed is the one who does so.
If a Gadol recites Halel, the listener is Yotzei, and responds Halelukah to whatever the Gadol says.
Depending on local Minhag, Pesukim are either repeated or not, and a final Berachah is either recited or not.
BEING MOTZI ANOTHER IN BIRKAS HA'MAZON
The Halachah is that a son (who is only obligated d'Rabanan because of Chinuch) may be Motzi his father (who is only obligated d'Rabanan by virtue of the volume of food he ate).
An Eved may be Motzi his master and a wife her husband (they are all on the same level of Chiyuv) but accursed is the one who does so.
THE CUSTOMS OF HALEL
(Rava): Halachos regarding the original institution of Halel may be inferred from the vestiges of those practices remaining today.
Responding Halelukah (the first word of Halel) at the beginning of Halel after the Chazan teaches us that it is indeed appropriate to respond Halelukah after the Chazan (at the start of the Halel).
Responding Halelukah a second time at the end of the first phrase of Halel teaches the Halachah (para. b) of our Mishnah.
Repeating Hodu LaShem teaches us that the listeners said the opening of each Perek.
(R. Chanan b. Rava): It is a Mitzvah to respond to the start of the Perakim.
Repeating Ana Hash-m Hoshiyah Na reminds us of the first Halachah of our Mishnah (a minor dictating Halel to an adult who repeats his words).
Repeating Ana Hash-m Hatzlichah Na teaches us the last Halachah of our Mishnah (permission to repeat).
He says Baruch Haba and the listeners respond with B'Shem Hash-m teaches Shome'a k'Oneh.
Question: Is one who hears, but does not respond, Yotzei?
Answer (R. Chiya b. Aba): Great people taught that one is Yotzei (Shome'a k'Oneh).
The source for Shome'a k'Oneh was taught by R. Shimon b. Pazi citing R. Yehoshua citing Bar Kapara as the Pasuk which speaks of Yoshiyahu as reading the Sefer.
The Sefer was read by Shafan!
This teaches Shome'a k'Oneh.
Question: Perhaps Yoshiyahu recited the words which Shafan dictated?
Answer (R. Acha b. Yakov): The Pasuk credits Yoshiyahu for his humility in the face of hearing the words.
NOT SPLITTING THE VERSE BARUCH HA'BA
(Rava): One should not pause for a breath between Baruch ha'Ba and b'Shem Hash-m in order to make it clear that it is one thought, and not a meaningless utterance of the Shem.