Is it permissible to transfer one's salary to an usurious bank and benefit only from the principal of the salary, while giving away all the profits? And are the quarterly profits from a savings account at Faisal Islamic Bank permissible, or are they usury? And are the profits from Abu Dhabi Islamic Bank in Egypt permissible?

It is not permissible to deal with usurious banks as long as an Islamic alternative exists, and ease of dealing with them does not make it permissible. The default ruling is that it is permissible to deal with Islamic banks, invest money with them, and benefit from their profits, unless a Sharia prohibition becomes evident. If there is a conflict in fatwas regarding a particular bank, then caution is warranted, and one should seek out a reputable Islamic bank and consult with specialized scholars in the country. The decisive factor in transactions is their reality, not their names, and some Islamic banks may resort to fictitious transactions.