Tashahhud of Hazrat ibnu Masood (Radiyallahu Anhu)

Q: My question is that I've heard that it can be wrong to say assalamu 'alaika ayyuhan Nabiyuu because the prophet sallallahu alaihi wassalam has passed away and instead we should say al-salaam 'ala al-nabi as said by Ibn Masood in Sahih bukhari. Now, majority scholars say that we should not change tashahud after the death of prophet sallallahu alaihi wassalam but my question is Ibn Masood knows better than all of the current scholars because he was a sahaba so shouldn't we follow him because he knows better the prophet sallallahu alahi wassalam?

Another issue I have is that I came across a hadith where prophet sallallahu alaihi wassalam said that no supplication is accepted unless we send peace and blessings on him. I don't remember the source of this hadith so maybe you know. So can u tell me if it mandatory to send blessings on the prophet sallallahu alaihi wassalam every time we make dua and if we forget, that dua will be incomplete?

Encouraging customer to take finance

Q: I want to sell my car and I know that in most cases, people will not be able to buy it cash. I know a car dealer who arranges finance from the bank for customers. Can I advertise the car and say that finance can be arranged, and when a customer comes to me, I will send him to the car dealer who I know will assist him with the finance? Will this be permissible?

Bribery

Q: The consultancy through which I am getting job in Saudi is asking for 1 lakh money for the job they are providing. Is it halaal to give money to them or is it just like bribery? Could you please help me out? The consultancy found the job for me in Saudi.

Written talaaq

Q: A woman had sent a khula letter on a 100 rupees stamp paper written by a moulana to her husband witnessed by her sister and brother stating that she needs khula, upon receiving the husband signed the document writing that he is giving divorce and willing to release her with out taking any Mahr amount or what so ever. Will this end the marriage or the husband should pronounce talaaq in front of witnesses to end the marriage. Just upon receiving the written consent papers can the woman marry another person.