Paying back a loan in a different currency according to the exchange rate

Q: Bakr and Zaid are travelling in a foreign country. Zaid takes a loan of 100 USD from Bakr. Bakr makes the condition that when they return to South Africa, Zaid must not pay him 100 USD, but rather the equivalent of 100 USD in South African rands. The equivalent of the 100 USD will be based on a mutually agreed exchange rate decided by Zaid and Bakr when they return to South Africa. Is this type of transaction permissible?

Taking a profit against a loan

Q: Is Islamic banking across GCC correct? they are referring to profit rate for car loan etc. Is this the same as interest? Am I safe to purchase a car through Islamic banking profit rate that they are referring. Bank says it is as per Shari'ah. Please help to sort this doubt as I am about to purchase a car and since I cannot afford full payment, I am preferring Islamic banking. Will I be in danger?

Greeting non-mahrams

Q: When a non-Mahram comes to my house accompanied by a Mahram, I shouldn't go and greet them right? Like two of my female cousins and my aunt. I shouldn't go to greet them, correct? Especially if one doesn't follow Islamic etiquette?

Hadith question

Q: The Messenger of Allah (Sallallahu Alayhi Wasallam) said: “Whoever says at the end of every Fajr prayer, while his feet are still folded, before speaking: ‘None has the right to be worshipped but Allah, Alone without partner, to Him belongs all that exists, and to Him is the praise, He gives life and causes death, and He is powerful over all things, (لا إله إلا الله وحده لا شريك له له الملك وله الحمد يحيي ويميت وهو على كل شئ قدير)’ ten times, then ten good deeds shall be wiped away from him, ten degrees shall be raised up for him, and he shall be in security all that day from every disliked thing, and he shall be in protection from Shaitan, and no sin will meet him or destroy him that day, except for associating partners with Allah.”

For this hadith, does this mean that it is impossible for a person to commit a sin on that day and does this include all major and minor sins? And is this Hadith graded authentic by everyone?