1)

(a)One cannot make an Eruv of food initially on Yom-Tov for Shabbos - because it is Hachanah, and we have already learnt that preparing on Yom-Tov for Shabbos is prohibited; whereas preparing on foot for the first time is permitted, because, as we have already explained, an Eruv on foot does not require verbal preparation, and is therefore not considered Hachanah.

(b)One is permitted to make an Eruv with bread on the second day, after having made it with bread on the first - provided one uses the same loaf.

(c)Not all Amora'im agree with Rav Ashi's proof from our Mishnah, which mentions the same loaf for the second day's Eruv as for that of the first - because in their opinion, using the same loaf might just be a good piece of advice, but not Halachically necessary.

2)

(a)Rebbi Yehudah permits placing two different Eruvin for the two days of Rosh Hashanah, enabling him to go in one direction on one day, and in the other direction, on the next - because in his opinion, the two days of Rosh Hashanah have two sanctities.

(b)Rebbi Yehudah permits taking Terumah (which is normally forbidden on Yom-Tov) on the first day of Rosh Hashanah on the condition that it is not Yom-Tov (because the second day is); then, on the second day, he repeats the procedure, taking Terumah on the understanding that the first day was Yom-Tov, and not the second.

(c)The Rabbanan prohibit both placing two Eruvin and taking Terumah on the two days of Rosh Hashanah (conditionally) - because they hold that the two days of Rosh Hashanah have one sanctity.

(d)They also argue by an egg that is laid on the first say of Rosh Hashanah: Rebbi Yehudah permits it on the second, the Rabbanan forbid it.

3)

(a)The reason that the Rabbanan (who argue with Rebbi Eliezer above, and hold that Shabbos and Yom-Tov have one sanctity), nevertheless agree with him that the two days of Rosh Hashanah have two - is because, unlike Shabbos and Yom-Tov which follow one another, where they are both holy, the two days of Rosh Hashanah are not; because Chazal only declared the second day Yom-Tov, if the first day was Chol.

(b)The Tana who argues with Rebbi Yehudah in our Mishnah, and who says that both days of Rosh Hashanah have one sanctity - is Rebbi Yossi, who prohibits, in a Beraisa, making two Eruvin (conditionally) on the two days of Rosh Hashanah.

(c)Rebbi Yossi proves his point - from the fact that if the witnesses (who testified that they had seen the new moon) arrived only after Minchah-time, they would treat the remainder of the first day, as well as the second, as being holy.

(d)The Rabbanan however, refute that proof - really, they counter, the first day ought to be Chol; but Chazal declared it Yom-Tov, in order that, in subsequent years, one will not remember how on that occasion, they later declared it Chol, and come to treat every thirtieth of Elul lightly (in spite of the fact that the witnesses might still turn up before Minchah (as they usually did).

4)

(a)Had Rebbi Yehudah confined his statement (that the two days of Rosh Hashanah are considered like one) to Eruvin - we would have thought that it is only there that he holds this opinion, because he did not do anything (on Yom-Tov); whereas by Tevel, where he actually separated Ma'asros, we would have thought that he may perhaps agree that it is forbidden to eat it on the second - in spite of the fact that they the two days are considered like one. And had he taught us these two cases - we would have thought that he is lenient there, only because there is no direct reason to issue a decree; whereas by an egg, where there is reason to decree because of its similarity to fruit that fell from a tree on Yom-Tov (and which is forbidden - in case one comes to climb the tree and pick it), or because of juice that flows or drips from the grapes (which is forbidden - because one may come to squeeze the grapes), maybe Rebbi Yehudah will agree that it is forbidden on the second day of Rosh Hashanah. And that explains why he needed to teach us his ruling in all three cases.

5)

(a)The Gemara initially quotes Rebbi Yossi as saying - 've'Chen Hayah Rebbi Yossi Oser bi'Shnei Yamim-Tovim shel Galuyos'.

(b)If Rebbi Yossi was really coming to forbid the second day of Rosh Hashanah in Galus (and not of Yom-Tov Sheni shel Galuyos), then he ought to have said 'ba'Golah' rather than 'shel Galuyos'.

(c)The Gemara finally explains Rebbi Yossi's statement to read - 've'Chen Hayah Rebbi Yossi Oseh Isur Sh'nei Yamim-Tovim shel Galuyos ki'Shnei Yamim-Tovim shel Rosh Hashanah, le'Rabbanan de'Sharu'.

(d)Rabah bar Shmuel quoted a Beraisa which he had heard from Rav, in which Rebbi Yossi agreed that the two days of Yom-Tov Sheni of Galus have two sanctities, proving Rav Sheshes' ruling wrong - that is why Rav Sheshes subsequently asked Rabah bar Shmuel not to tell Rav Nachman and Rav Chisda what he had learnt from Rav.

6)

(a)According to Rav Ashi's version of the story with the deer - the deer had come from outside the Techum on that day, and that was why Rav Sheshes declined to eat it.

(b)In the original case (when the deer was trapped on the first day of Yom-Tov) - Rav Sheshes would have eaten it without hesitation.

(c)According to Rav Ashi - Rav Sheshes never made such a request from Rabah bar Shmuel. In fact, that part of the story did not take place.

(d)Rav Ashi explains the Machlokes like this: - Rav Nachman and Rav Chisda maintain that since gentiles brought the deer into the domain of the Resh Galusa for the Resh Galusa, it is permitted for others to use it; whereas Rav Sheshes holds that whatever the gentiles brought to the Resh Galusa, was intended for all the Rabbanan who were assembled there, too.