Is it permissible for one to shake hands with his uncle`s daughter?
No, it isn`t because he is a non-Mahram (Marriageable) to her.
Is it permissible to offer prayer at home, or should it be offered in the mosque?
All perfect praise be to Allah, The Lord of The Worlds. It isn`t preferable for the man to pray at home as praying in the mosque is twenty seven times more rewarding. Therefore, this should motivate him to offer prayers in the mosque. And Allah Knows Best.
If a traveler settles or a sick person recovers while fasting, is it permissible for them to break their fast?
● If a sick person starts the day fasting and then recovers during the day, they must complete their fast.
● If a traveler starts the day fasting and then settles (returns or stops traveling) during the day, they must also complete their fast.
● It is forbidden for both of them to break their fast because the concession (rukhsah) is no longer valid once its reason disappears.
Is Fajr (dawn) Sunnah a confirmed one?
All praise be to Allah The Lord of The Worlds Of course, it is a confirmed Sunna which the Prophet (PBUH) used to offer in a regular basis. And Allah Knows Best.