Holiness, Females & Tefillin Based on a reponsa from Rav Hershel Schachter

(2) There were courtyards in Jerusalem built on rock and below them was hollow because of graves of the deep. [Stepping over a human grave causes ritually impurity, which can be blocked by a sufficiently wide space between the body and the covering; by building a courtyard over a hollow, one guarantees that any graves which are too deep to be discovered can not make people in the courtyard above impure.] They would bring pregnant women to there [these courtyards], and they would give birth there and raise their children there [to ensure that the children never become ritually impure]. They would bring oxen and on their backs slats [literally: doors] and the children would sit on top of them with stone cups in their hands. When they reached the Shiloach [stream], they would descend and fill [the cups], and remount and sit atop them. Rabbi Yose says: From his place [atop the oxen] one would lower and fill [his cup because of the fear of a grave in the depths].

In order not to belittle/ cheapen it (the Para Aduma) - ie: since tvul yom (a person with lesser status of purity) is kosher to perform the service with the Para Aduma, (the inference is that) we don't need to be so careful with its purity, therefore they (the sages) made many stringencies regarding its purity with this being one of them.

§ The Gemara now considers which prohibitions are permitted in times of mortal danger. Rabbi Yoḥanan says in the name of Rabbi Shimon ben Yehotzadak: The Sages who discussed this issue counted the votes of those assembled and concluded in the upper story of the house of Nitza in the city of Lod: With regard to all other transgressions in the Torah, if a person is told: Transgress this prohibition and you will not be killed, he may transgress that prohibition and not be killed, because the preserving of his own life overrides all of the Torah’s prohibitions. This is the halakha concerning all prohibitions except for those of idol worship, forbidden sexual relations, and bloodshed. ...

§ When Rav Dimi came from Eretz Yisrael to Babylonia, he said that Rabbi Yoḥanan said: The Sages taught that one is permitted to transgress prohibitions in the face of mortal danger only when it is not a time of religious persecution. But in a time of religious persecution, when the gentile authorities are trying to force Jews to violate their religion, even if they issued a decree about a minor mitzva, one must be killed and not transgress. When Ravin came from Eretz Yisrael to Babylonia, he said that Rabbi Yoḥanan said: Even when it is not a time of religious persecution, the Sages said that one is permitted to transgress a prohibition in the face of mortal danger only when he was ordered to do so in private. But if he was ordered to commit a transgression in public, even if they threaten him with death if he does not transgress a minor mitzva, he must be killed and not transgress. The Gemara asks: What is a minor mitzva for this purpose? Rava bar Yitzḥak says that Rav says: Even to change the strap of a sandal. There was a Jewish custom with regard to sandal straps. If the gentile authorities were to decree that Jews must change their practice and wear sandal straps like those worn by the gentiles, one would be obligated to give up his life rather than veer from the accepted custom.

(3) Women and slaves are exempt from Tefillin because it is a positive commandment which is caused by time. Rem"a: And if the women want to be stringent for themselves, we protest against it (Kol Bo).

(3) They combined against Moses and Aaron and said to them, “You have gone too far! For all the community are holy, all of them, and the LORD is in their midst. Why then do you raise yourselves above the LORD’s congregation?”