Is it a condition that one should offer two sacrifices for a male newborn?
It is desirable to offer two sheep for a male newborn, and one for a female newborn. Offering one sheep for the male newborn is also permissible as it observes the Prophet`s Sunnah in this regard.
Does sacrificing one sheep avail for the entire household?
Praise be to Allah, and peace and blessings be upon our master, the Messenger of Allah.
In Islamic jurisprudence, the sacrifice (Udhiyah) is considered a Communal Sunnah (Sunnah Kifayah) for the members of a single household who share the same financial support.
If one member of the household performs the sacrifice—even if they are not the primary breadwinner, such as the wife or one of the children—the religious request is fulfilled on behalf of the entire household. This is similar to the Funeral Prayer (Salat al-Janazah), where the obligation is dropped for the community if some perform it.
While the communal request is satisfied by one person's action, the specific spiritual reward (Thawab) for the act of worship belongs only to the person who sacrificed, unless that individual explicitly intends to include the other family members in the reward.
A single sacrifice also avails for a man who is married to more than one wife. And Allah the Almighty knows best.
Is it permissible for the guardian to give Sadaqa (voluntary charity) from the money of the orphans?
It is impermissible for the guardian to donate from the money of the orphans because he is entrusted with the safekeeping of that money, and is prohibited from donating it.
What is the ruling on Friday Ghusl (ritual bath)?
Friday Ghusl is a confirmed Sunna (Prophetic tradition) even if a person wasn`t in a state of Janbah (ritual impurity), or physically unclean. However, one who doesn`t make Ghusl on Friday isn`t sinful for the Prophet (PBUH) said: "It is good for a Muslim to make ablution for Friday prayer, but it is better to make Ghusul. [At-Tirmithi & Abu Dawood].