Engels was not in charge of the business he was sent to Manchester to join - a cotton thread factory. It was majority-owned, and run, by his father's business partner, Peter Ermen.

Ermen suspected that the younger Engels had been sent to spy on him, so he refused to place him in positions where he had much responsibility or participated in strategic decision-making. Engels was largely restricted to mundane clerical duties in what he called "the bitch business", spending 20 years maintaining an extensive correspondence with suppliers and clients, while systematically raiding Ermen's petty cash box for some of the funds he passed on to help support his colleague Marx.

As for the living conditions of employees, it was horror at the appalling slum conditions that he found in Manchester that prompted Engels to write his first book, The Condition of the Working Class in England and which inspired much of his radicalism. It's well worth mentioning in this connection that, while Engels had the money to live comfortably, and from a social point of view was expected to do so, he actually preferred to spend most of his time living in cheap lodgings under an assumed name with his mistress, an Irish worker named Mary Burns.

I have written in much more detail about Engels's time in Manchester, conditions in the city, and his relationship with Mary Burns, here. It's a fascinating story.