Is permissible to buy/sell with non-Muslim?
Yes buying/selling for a Muslim with non-Muslim is permissible as regards what is lawful.
Who is obligated to fast?
The one obligated to fast is the Muslim who is of sound mind, mature, capable of fasting, and free from obstacles such as menstruation or postpartum bleeding. And Allah Knows Best.
Is Buying a house in installments through banks?
Taking a loan from interest-based banks is prohibited and considered a major sin. Instead Getting a loan from Islamic banks is considered Murabaha and can be used as an alternative, provided all the necessary Islamic conditions are met. And Allah Knows Best.
Is it permissible to donate corneas to Jordan Eye Bank or all the organs via telephone?
All perfect praise be to Allah, The Lord of The Worlds, and may His Peace and Blessings be upon our Prophet Muhammad and upon all of his family and companions.
Corneas donation that is carried out after one's death is permissible by the Board of Iftaa'. Because this procedure is highly sensitive, the donation process
should undergoes to an accredited mechanism. And Allah, The Exalted, Knows Best