What is the Islamic ruling regarding a person finding buried treasure, whether gold or artifacts, and what is their share of it?
If the buried treasure is Islamic, it is considered Luqta (lost property), and the finder must announce it to locate its owner. If all efforts to find the owner fail, the finder may take ownership of it. If the treasure is non-Islamic and consists of gold or silver, zakat must be paid on it, which is one-fifth of its value. And Allah Knows Best.
Is it incumbent on a father to cover the marriage costs of his son if the latter couldn`t afford them?
The son should seek the help of his relatives in order to convince his father to do the aforesaid, and the father should make sure that his son doesn`t commit fornication through helping him to get married, and Allah will reward him for doing so.
Is it permissible to offer the Eid sacrifice in a non-Muslim country?
Eid sacrifice is permissible anywhere, and Islamic Sharia hasn`t determined that it should be in an Islamic country, but poor Muslims should be given a share in order for it to be valid since it is an act of worship. A portion of that Eid sacrifice should be given at least to one poor Muslim, and if that wasn`t possible then the one offering it should consume it along with his family.
Should vowed fast be offered in consecutive days, or not?
Vowed fast should be offered in line with what was originally intended by the vow-maker, either consecutively, or not.