Brand new on hardware yes. On band made out of fabric, maybe. It would depend on how bad it was. But I never buy fabric watch band so I've never had to deal with such a thing. I love the milanese stainless band. BUt other watches i"ve always gotten leather. If those had bad imperfections or blemishes I would exchange. If it just a little bit of thread poking, I'd probably just cut it or shave it off and call it good.
No, they would not. I'd either not notice or not care. Imperfections on the watch, sure, that would bother me. On the band, not really since it's a wearable "part" and made of fabric.
It certainly wouldn't worry me, but as it's obviously a concern for you, imagine what that fabric band will look like after a year or so of wear - even if worn occasionally. It sounds as if a more 'sturdy' metal band would be more compatible for you.
As a long time collector and lover of automatic watches (never had an Apple watch) I've always preferred leather or stainless straps over fabric as they are far more durable & comfortable - if chosen correctly.