The trick is to change your perception.
None of these are show stoppers. They're not even really problems if you put on your rose-tinted glasses. This is a list of OPPORTUNITIES!
Maybe I'm a little crazy but I kind of like a big screw-up, as long as it's not on something I'm desperate to finish on a deadline. A big screw up can lead to some seriously creative thoughts, and sometimes the "repair" or the plan B ends up much more interesting than the original idea.
Of course, most of my quilts are scrappy or at least have some sort of scrappy element to them, and I think that lends itself to "creative fixes" a little more easily than a more regimented quilt pattern/style would. But all in all...if there's no deadline, to me a screw up means it's time to have some good creative fun!