1) When we daven Shemona Esrei, it is considered as if we are "Omed L’fnei Hamelech- standing before the king". We are fortunate to be granted an audience with the King [of kings], 3 times daily, every single day of our lives! We must realize the awesomeness of this opportunity, and not take it for granted.
2) The Shemona Esrei Tefilah is divided into three parts; the first three Brachos are compared to a servant that is praising the master, the middle Brachos are compared to a servant asking for compensation from the master, the last three Brachos are like a servant giving gratitude to the master. (Obviously, the metaphor here is that we, members of Klal Yisroel, are servants to our master, the master of the world, Hashem)
During the first three Brachos as well as the last three Brachos of Shemona Esrei (which are praise of and thanks to Hashem) we are prohibited from asking for any personal requests.
If the requests are for the sake of the public, they are permitted at any point of Shemona Esrei, even during the first and last three Brachos. (Hence, Yaaleh V’Yavo, Al Hanisim, are interjected into the Bracha of Hoda’ah, Zachreinu L’Chaim and Mi Kamocha are interjected into the Bracha of Avos during Aseres Yemei Teshuva, etc.)
Reader's Question:
On Erev Shabbos Parshas Lech Lecha you wrote: " Between the parshiyos (Bein Haperakim of Shema) gesturing is permitted for the sake of a Mitzvah, according to all opinions". What about answering "Amen" Bein HaPerakim??
My Answer
Here is the long answer starting with halahos for B'Emtza Haperek (which you didnt ask me about), and then addressing your question (Bein Haperokim):
If one is in the midst of one of the Birchos Krias Shema, and even during Krias shema itself (besides for during the first Posuk and Baruch Shem), the following "Amen's" may be answered: 1) after the Bracha of Hakel HaKadosh 2) after the Bracha of Shomea Tefilah 3) Amen Yehei Shemi Rabbah (without adding the words Yisbarach etc.) 4) the Amen after " D'Amiran B'Alma V'Imru Amen" in Kadish 5) the verses "Kadosh Kadosh" and "Baruch Kevod" in Kedusha may be answered as well. 6) Borchu 7) when the congregation is saying Modim, only the first three words "Modim Anachnu Lach" may be said. 8) Amen to the Pesukim of Birchas Kohanim (but not to the Bracha that that the Kohanim make before starting Birchas Kohanim) 9) The verse "Shma Yisroel" in Kedusha of Musaf on Shabbos (according to the Aruch Hashulchan. The Mishna Berura and others argue and prohibit).
The rest of the Amen's in Kaddish (which are only a Minhag and not M'Dina D'Gmara) and Chazaras Hashatz, or any other Bracha one hears, and the rest of Kedusha may not be answered.
However, if one is holding "Bein Haprokim" (between the parshiyos of Krias Shema, or between two Brachos of before or after Krias Shema) he may indeed answer Amen to any Brachos that he hears.(even if they were recited by a Katan (a minor). However "Baruch Hu U'Varuch Shemo" should not be answered. The exception to this is Kaddish and Modim D'Rabbanan, where he may only interrupt for the Amein's that are permitted "B'Emtza HaPerek" (during Krias Shema or its Berachos) as we described above
Our holy sages, the Chazal tell us תנא דבי אליהו כל השונה הלכות בכל יום מובטח לו שהוא בן עולם הבא, שנאמר הליכות עולם לו, אל תקרי הליכות אלא הלכות - one who studies [at least two] Halachos daily is assured a portion in Olam Haba - the world to come. (:מגילה כ"ח )