Is buying shared land from someone who has taken possession of it considered halal or haram?
The shared land is possessed by the country i.e. for all people; therefore, it shouldn't be possessed/occupied save by it's guardian/owner permission,thusly it can't be possessed save by having owners' permission. Finally, buying it from a person who don't possess it is impermissible. And Allah Knows Best.
Is it permissible for a person who broke fasting in Ramadan because of being sick to pay a ransom?
If there is hope for him/her to be cured, then he would be required to make up for the missed fasting days when he/she recovers, and no ransom is due on him/her. If his/her disease is incurable, then he/she would be required to pay a ransom for each missed fasting day, which is (600) grams of wheat, or rice. And Allah Knows Best.
Is it permissible to trim the eyebrows if they become excessively long?
Trimming eyebrows is permissible if they become excessively long, yet; it is reprehensible. And Allah Knows Best.
I swear that I will leave the religion of Allah if I return to smoking" and then returned to smoking. What is the ruling?
Whoever conditions disbelief on something and intends to disbelieve if it happens, he becomes a disbeliever immediately. Therefore, you must pronounce the two testimonies of faith (Shahada) and reconcile with your wife if she is in her waiting period (Iddah). It is recommended to consult the Department of Fatwa for further guidance. And Allah Knows Best.