Very quickly review גמרא דף לח עמוד א from אמר רבא (last line) until דף לח: “אמר רבא (three lines from the bottom of the Amud)
The Gemara lists six halachos /minhagim of how they would read Hallel in the time of the Gemara.
The תוספת דף לח: “הלכתא notes that already in his times the reciting of Hallel was not in accordance with the minhagim of Rava and says since they were just customs if the custom was accepted to be different than no issue of not following the original custom of Rava.
Question:
Rashi says the first halacha/ minhag – there is a mitzvah for the public to respond the word הללויה after the Chazzan at the opening of Hallel. This applies to everyone even to people who know how to recite Hallel on their own.
Why do we not follow this halacha when we recite Hallel?
For an explanation learn the ר”ן דף י”ט. דפי הריף “הוא אומר הללויה
https://hebrewbooks.org/pdfpager.aspx?req=14319&st=&pgnum=620
and ערוך לנר https://hebrewbooks.org/pdfpager.aspx?req=14414&st=&pgnum=148
In regard to repeating the ראשי פרקים
Would the public repeat the opening line only after the Chazzan said the opening line or after each line recited by the Chazzan of that paragraph?
When would the public respond with the word הללויה?
Learn תוספת “מכאן שמצוה and the מאירי https://hebrewbooks.org/pdfpager.aspx?req=57966&st=&pgnum=105
Questions:
Rashi “הוא אומר הללו עבדי” concludes that only someone who does not know how to recite Hallel can rely on the reciting of the Chazzan by responding הללויה.
What is Rashi’s source for this stringency?
Since we have a rule of שומע כעונה –
Why can’t everyone rely on the reading of the Chazzan?
And what is the need for the listener to respond to the Chazzan with the word הללויה?
Learn מגן אברהם אורח חיים ס’ תכב ס”ק ה
https://hebrewbooks.org/pdfpager.aspx?req=14325&st=&pgnum=287
and ביאור הלכה “הלל
https://hebrewbooks.org/pdfpager.aspx?req=60389&st=&pgnum=184
Learn תוספת “שמע ולא ענה
Questions:
How does Rashi answer Tosfos question from the Gemara in Brachos?
Learn ר”ן דף יט: דפי הריף “וכתב רש”י (third line from top of the Amud)
What is the point of disagreement between Rashi and Tosfos?
See קהילת יעקב ברכות ס’ י”ג who presents a חקירה in the concept of שומע כעונה
Learn ריטב”א “הוא אומר ברוך who gives a different explanation as to why שומע כעונה does not help for the individual who is middle of his silent shmoneh esreh.