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 a person rewarded for refraining from all that breaks their fast when required to do so, and is it considered a valid fast?
If a person eats or drinks thinking that Fajr has not yet arrived, but then someone informs them that Fajr had already begun, they must refrain from eating for the rest of the day and make up the fast later.
If they observe the required restraint (imsak), they will be rewarded for obeying the command because fulfilling an obligation brings reward.
However, this is not considered a valid fast in terms of rulings. For example:
● It is not disliked (makruh) for them to use a miswak after noon.
● They are not encouraged to hasten the breaking of the fast at sunset.
● Other fasting-related rulings do not apply to them.
Which is more excellent for a woman: to pray in the mosque or in her house?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
Our Master the Prophet ﷺ said: 'It is more excellent for a woman to pray in her house than in her courtyard, and more excellent for her to pray in her private chamber than in her house.' Therefore, a woman’s adherence to her home and her refraining from going to the mosques—in obedience to the command of Allah the Exalted—attains a great reward and abundant recompense. Furthermore, women praying in congregation within their homes is better than their attendance at the mosques, based on the aforementioned Hadith. And Allah the Exalted knows best.
What is the ruling of Islamic Law on kissing while fasting?
All praise is due to Allah, and peace and blessings be upon our master the Messenger of Allah ﷺ.
It is prohibitively disliked (makrūh taḥrīman) for a husband to engage in foreplay with or kiss his wife during the daylight hours of Ramaḍān if doing so stirs his desire. If pre-seminal fluid (madhī) is released as a result, the fast is not invalidated; however, if seminal fluid (manī) is released, the fast is broken.
Imām al-Khaṭīb al-Sharbīnī, may Allah have mercy upon him, stated: "It is prohibitively disliked to kiss — whether on the mouth or elsewhere — for one whose desire is stirred, whether man or woman, to the extent that he fears it may lead to intercourse or ejaculation. Embracing, touching, and similar acts without a barrier carry the same ruling as kissing in this regard, because such acts expose the act of worship to being corrupted — and as the two Ṣaḥīḥs record: 'Whoever circles around a protected boundary is liable to fall into it.'"
He further added: "It is preferable for one whose desire is not stirred — even if he is a young man — to refrain from such acts as well, so as to close the door entirely. For he may believe his desire has not been aroused when in fact it has. Moreover, it is Sunnah for the fasting person to abstain from all desires without exception." — Summarised with minor adaptation from [Mughnī al-Muḥtāj]. And Allah the Almighty knows best.