Correct, I have not owned a sweater for many years now, don't need them. Sweat does shirts no harm whatever, all mine are made by Ascot Chiang in Hong Kong and none over a twenty year period has suffered any harm.
"Finance" is a very broad church and does not help over much but there is nothing inherently wrong with it for business use.
What is of greater concern is who "E Thomas" the cloth supplier actually is and whether "Super 150" is robust enough. However if it one of half a dozen in use it should not come to much harm. Expensive for what it is and from it you have bought it.
That is still a suit jacket and my original comments apply equally to that as well.
A suit jacket is simply not a blazer.
Cut to answer your second question, the number of times people have put up a suit jacket because the trousers had been injured and it looks no more right now as then. Ignore shops, they will tell you anything that they think you believe to get merchandise out of the door.