It can take a bit to figure out how to post here, there are some great stickied help over here:
https://www.quiltingboard.com/qb-help-center-f27/
For backs, the best solution is always to have "plenty" whatever that means to you. Obviously if you are working on a small wall project an 1" might be plenty whereas on a king sized top that would make any of us choke (plus the fabric contracts and such as it is quilted...). But this idea of having plenty, well, that gets costly which is part of this thread. I love the extra wide fabrics but I also like being straight of grain. I've found that to make sure my piece is not some sort of parallelogram and I can do a ripped edge, I need to order an extra half yard/18 inches of fabric! Can't tell you how many times the pieces are cut badly and it is not all on the shops but also on how it is wound/folded on the bolts.
When you have to seam, I think generally a 1/2" open pressed seam is advised for backs. Yes, use a nice small stitch and cut off selvedges.
A small busy print hides many imperfections and is a perfect choice for a back!
There is nothing that will point out every imperfection so nicely as a plain white sheet. Just don't do it!
For all of us, we work so closely with our projects and are aware of every imperfection. We know we bobbled that line down there or whatever and so we see it. Once you get back a bit in either space or time, it all gets harder to see. We have a quilting saying about being good enough if you can gallop past on a horse and not see it. And that your friends either don't tell you or don't see it anyway -- or maybe they weren't your friends in the first place.