Returning items not purchased to the seller

Q: Two people are partners in a grocery shop. One is Deeni conscious and the other is not. Hence, it leads to many disputes. One particular dispute is that sometimes, there is an extra product delivered to the shop. One partner wishes to return it and the other wishes to keep it. The Deeni conscious brother keeps quiet in order to maintain the peace. Is this (keeping silent) correct? If not, what should he do for the future? This has happened in the past also where the product was not returned. What should he do to make amends for that?

Is this story authentic?

Q: There is story about a sahabi who went out in path of Allah and prior to leaving said regarding his pregnant wife: i leave what is in the belly of my wife in Allah's care. When he got back he found that his wife had passed away but his child was found living next to the grave. Is this story authentic?

Imaam leading the Salaah with his trousers below his ankles

Q: In the area that I've moved to, the imaam of the local Musjid leads the Salaahs with his trousers below his ankles. Does it diminish from the Musallis reward to follow such an imaam and is it permissible?

Also, after every Salaah, the imaam systematically makes the same short dua after reciting taqdeer once and istigfaar thrice, followed by Ayaatul Kursi, Tasbeeh-e-Fateemi, the fourth kalimaah thrice, and then the same lengthy dua after each Salaah. Is this allowed? And if not, Should I as a Musalli remain in the gathering so as not to create any conflicts with the locals, or rather just leave and perform my Sunnahs?