Can I start fasting based on the moon sighting of another country?
You must follow the moon sighting of the country you are in.
Should missed Sunnah prayer be made up?
Making up missed voluntary acts of worship is from Sunnah.
What is the ruling on someone who dies while having missed fasts?
● If a person dies before having the opportunity to make up the missed fasts—such as someone whose excuse (e.g., illness) persisted until their death—then no makeup fast (qada), fidyah, or sin applies to them.
● However, if they had the ability to make up the fasts but did not do so before passing away, the missed fasts must be compensated by giving a mudd of food for each missed day from their estate.
The Prophet ﷺ said: "Whoever dies while having a month’s fast due, one needy person should be fed per day on their behalf." [Narrated by At-Tirmidhi]
Additionally, a guardian (wali) may fast on their behalf, as the Prophet ﷺ said: "Whoever dies while having missed fasts, their guardian should fast on their behalf." [Narrated by Al-Bukhari and Muslim]
In another narration: "If they wish." This indicates that both feeding the needy and fasting on behalf of the deceased are permissible options.
Are the mother's maternal and paternal uncles, and the father's maternal and paternal uncles, considered among the unmarriageable kin (Maharim)?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
A mother’s maternal uncle and her paternal uncle, as well as a father’s maternal uncle and his paternal uncle, are all considered among the unmarriageable kin (Maharim). And Allah the Exalted knows best.