In the story of Mereimar and Mar Zutra who would gather 10 people. Rashi notes that they would pray first and then come to give their lecture. However, he also says that during the lecture the zman for shema would be reached. Is Rashi implying that Mereimar and Mar Zutra prayed before the zman? There are multiple other opinions and customs listed but its common to all the opinions that shema must be said at the right time
Also, by the way, why couldnt they stop the lecture and have the whole congregation pray together. Isnt that better than the bother of waking up extra early or the whole congregation slipping away one by one. thank you.
SC, Brooklyn, NY
This is an excellent Diyuk in the words of Rashi. Yasher Ko'ach for pointing it out.
I did not find anyone who deals with this Rashi specifically, but I recently learned the Gemara in Yoma (37a) that can explain your question.
The Gemara there says that one who recites Shema with the Anshei Mishmar -- who recite Shema before daybreak -- does not fulfill his obligation.
The Ritva and Gevuras Ari there comment that this does not mean that they totally did not fulfill their obligation, for if that were the case, then why did the recite the Shema then in the first place? Therefore, both explain that the Anshei Mishmar recited Shema before the optimal (l'Chatchilah) time, which is right before sunrise but after Alos ha'Shacher, and they fulfulled their obligation b'Di'eved.
According to this, we can understand the words of Rashi that you mentioned. Mereimar and Mar Zutra recited Shema after Alos ha'Shachar, but the rest of the students waited to say Shema at the optimal time.
Concerning your second question: Chazal gave great importance to learning together (in a Tzibur), especially before Yom Tov, to such a degree that it overrides even praying with a Minyan.
Kol Tuv,
Dovid Bloom