(a)

1. I have not found anyone who discusses this question explicitly, so I will try to suggest my own solution, but the matter might still require further thought.

First, I should point out that the Shulchan Aruch (Orach Chaim 73:3) writes that not only do they say Shema but they also recite Shemoneh Esreh. However, the Mishnah Berurah (#10) writes that many authorities maintain that since Tefilah is only mid'Rabanan, one may be lenient not to say Shemoneh Esreh since the dead body is lying in front of him.

2. One sees from this that according to many Poskim, one should say only the absolute miminum d'Oraisa requirement under these circumstances. The question now is whether the recital of Birkos ha'Torah before Keri'as Shema is d'Oraisa.

3. See Shulchan Aruch (OC 65:2) concerning one who entered a synagogue and found the congregation saying Shema. The Halachah is that he should say the first verse of Shema together with the congregation even though he has already recited the Shema himself.

4. The Mishnah Berurah (#8) writes that if he has not yet recited Shema, then his obligation to say Shema is even greater. The Mishnah Berurah adds that even if he has not yet said Birkos ha'Torah, he should still say the first verse since he is not saying it with the intention of learning Torah. The Mishnah Berurah concludes that he should be careful not to say more than the first verse (since the extra verses would be considered as learning Torah, which do require Birkas ha'Torah; see Sha'ar ha'Tziyun #11).

5. According to the above, I suggest that the people who slip out of the Hesped to say Shema do not need to say Birkos ha'Torah before Shema. My reasoning is that there is a difference between the people who slip out of the Hesped and the person who enters a synagogue and finds everyone saying Shema. The difference is that the people slipping out of the Hesped are required to say the whole of Shema because they may not have time afterwards. Therefore, it is not considered that they are learning Torah but rather they are performing the Mitzvah of Shema. It follows that even though the Mishnah Berurah (46:27) writes that the custom is not to say any verses at all before Birkos ha'Torah, nevertheless in the case of the people with the dead body in front of them -- who should say only the absolute miminum -- they should not say Birkos ha'Torah because they rely on the Din Torah and it is not necesary in this case for them to follow the custom, just as we saw that many Poskim hold that one does not even say Shemoneh Esreh.

6. In contrast, the reason why the person who enters a synagogue and finds everyone saying Shema should say the first verse is that otherwise it looks as if he does not wish to accept upon himself the burden of the Heavenly Kingdom, since everyone is saying Shema apart from him. To absolve himself of this suspicion it is sufficient to say only one verse, and any additional verses are considered as learning and require Birkos ha'Torah.

7. Here are further sources to support my argument that according to some opinions saying Shema is not considered as learning Torah, but rather it is similar to praying, and therefore in the case of the people present with the dead body at the Hesped, it is preferable to return immediately to the eulogy and not spend time saying Birkos ha'Torah.

(1) The first source is the Beis Yosef (Tur Orach Chaim 47, the chapter which deals with the Halachos of Birkos ha'Torah, end of DH v'Im Ba Lilmod). The Beis Yosef writes that reciting the Shema is not considered as studying Torah, and therefore if one had not said Birkos ha'Torah early in the morning and afterwards one said "Ahavah Rabah" immediately before Shema, it is still necessary to learn immediately after one finishes Davening. Even though "Ahavah Rabah" is considered as Birkos ha'Torah, nevertheless we see that saying the Shema is not considered as learning and therefore one must learn something else so that Ahavah Rabah can be considered as Birkos ha'Torah which applies on what one learns afterwards.

(2) The Beis Yosef explains that Keri'as Shema is considered as supplications and prayer; not as learning Torah. Learning Torah differs from praying, and saying the Shema is equivalent to praying.

(3) Another source is the Pri Megadim, cited by the Mishnah Berurah in Bi'ur Halachah #52, um'M. The Pri Megadim writes that if a person had not yet said Birkos ha'Torah and then forgot and started to say the blessings of Keri'as Shema, he should have specific intent not to be Yotzei Birkos ha'Torah by saying Ahavah Rabah, and then he may say Birkos ha'Torah after Shemoneh Esreh.

One sees clearly from the Pri Megadim that it is permitted to say Keri'as Shema before one has said Birkos ha'Torah if one did not intend to perform the Mitzvah of learning Torah by reciting Shema, but rather merely to perform the Mitzvah of saying Shema.

(4) It is preferable, ideally, not to rely on the above opinions of the Beis Yosef and the Pri Megadim. This is because the Mishnah Berurah (52:9) disagrees with the Pri Megadim, and in addition the Mishnah Berurah (46:27) writes that the contemporary custom is to say Birkos ha'Torah immediately after Asher Yatzar and not to say any verses before Birkos ha'Torah.

(5) However, for the question we started with, namely the people together with the Mes for whom the Mishnah Berurah cites many opinions that they should not even say Shemoneh Esreh, it seems that it is preferable to rely on the above Beis Yosef and Pri Megadim, and say Shema without Birkos ha'Torah beforehand.

(b) There are two ways of answering this question, given by different commentators cited in Ein Yaakov.

1. The Mefaresh "ha'Kotev" explains the difference between the verse in Nechemyah 9:33, "And You are righteous concerning everything that happens to us, because You have done the truth, and we have been wicked" (which we recite in Selichos) and the prayer that Abaye disapproved of in our Gemara. The difference is that in Nechemyah we merely justify all that Hash-m does to us, while in our Gemara we say that we have not yet been repaid for our sins, which implies that we are asking Hash-m to punish us.

In other words, in Selichos we mention what has happened in the past, while in our Gemara we make a hint at what might happen in the future, which is unnecessary and dangerous.

2. The Iyun Yakov suggests that it is possible that Abaye taught that the advice against opening one's mouth to the Satan only applies on specially tragic occasions, when the Midas ha'Din, the attribute of strict judgement, has been stretched out over the mourners. The Satan tries especially hard to accuse us at times of danger, such as during the seven days of mourning, when the Midas ha'Din is acting strongly against the mourner and his household. Therefore, at such a time a person should be particularly careful about the way he talks, which is why Abaye disapproved of the prayer said by the mourner, but at other times one does not have to be so very careful about what one says, which explains why in other prayers we mention our forthcomings.

Thank you for your interesting question!

Dovid Bloom