#1 is a very common problem. Ruffly borders. Easy to accomplish by taking a big hunk of fabric and just keep sewing until the pieced top runs out, then whack off the remaining length. Sigh. NO. Measure the top through the middle and cut that border to that length (and remember that you have TWO of them that ARE supposed to be the same, one on each side). Then quarter mark the top and border, match them up, and pin. Then do the same for the other border.
#2 - the frequency of this is not as common. Leave as many threads as possible sticking out the top side of the seams. Aaargh. Honest - you can clip these off yourself! You won't wear out your scissors! If I left these the way the quiltmaker did, this quilt would look pretty awful. So I remove them while practicing DH's Garage Language. Yeah - use your imagination.
#3 can be dangerous for your quilt. Longarm machines have a presser foot that hops. Your quilter is often NOT watching the foot. She's probably watching the pattern that she is quilting from because she's following the design using a laser light. When the foot 'hops' into that hole in your seams, the machine is going to stitch itself right into your quilt. The poor quilter may have to cut your quilt to extricate the machine - that is not a comforting thought.
This happened to be in a "good" spot. I was able to flip the border up and stitch the seam closed with the longarm, but that is a rare bit of serendipity. Yes, it was stitched right through the batting and backing, but the thread was a perfect match for the backing and that little seam does not show.
#4 on this particular quilt, as if there wasn't already enough going on, the backing was not long enough. I had to cut some length off the end, then piece it, and attach it to the perpendicular end. I changed it from a measurement of 40 x 70 to 45 x 60. Or something like that. My usual system is that customers bring their quilt here. I measure everything, check the batting & backing sizes, price out the work with an estimate, and we're good to go. For this "sweet little old lady" I pick up and deliver when I have a dinner date with my friends in her neck of the woods. She's either throwing a bag of work at me and trying to get rid of me because she's going to be late for her 4:30 dining room booking, OR she's trying to pawn off a bunch more quilting stuff that she found in her spare room/storage locker/under the kitchen sink. In any event, I don't check sizes of anything, and that occasionally bites me in the arse.
After finishing THREE of her quilts on Wednesday, I drank myself out of house and home that night. It was a happy accident that I went to a quilting event the next evening, AT A WINERY. HAH! SCORE!