What is the ruling on exchanging kisses and hugs between husband and wife during the day in Ramadan?
Praise be to Allah The Lord of The Worlds.
It is disliked to kiss one`s wife during the day in Ramadan, and it is recommended to avoid that. And Allah The Almighty Knows Best.
What is the ruling on one who slept while firmly seated on the ground, regarding nullification of ablution?
The default ruling regarding sleep is that it nullifies ablution. An exception to this is one who slept while firmly seated on the ground; his ablution is not nullified by sleep if he wakes up while still firmly seated on the ground. And Allah the Almighty knows best.
Is it permissible for a Muslim woman to wear trousers at home?
Wearing trousers at home isn't prohibited so long as non-Mahrams do not see her. And Allah Knows Best.
Is it permissible for a guardian (Big brother) to unlawfully stop his sister from getting married?
If the guardian denies her right in getting married for an unlawful reason, she should go to court in order to settle that matter, and the guardian is considered sinful in this case.