The brick-maker is alluding to the fact that the company's new men were hand picked and connected..... that they had high morals and were virtuous. These men were a threat to the senior workers, as they were believed to be replacements.
The ship cannot be repaired because they have no pistons and must order them.
The manager claims to have a great relationship with Kurtz, but that is a lie. He is happy to take advantage of the circumstances, which delay getting someone to help Kurtz, who is believed to be ill.
The pilgrims are actually a group of men called the Eldorado Exploring Expedition. Marlow is being sarcastic when he calls them pilgrims, as pilgrims journey for sacred purposes..... not for money.