There is a good chance that most of us here remember the first mark on our basses. Mine was in a bass lesson. My teacher was eating dinner while teaching, hand talking, and managed to fork the top of my instrument. It was a tiny little mark probably smaller than yours. My teacher had to sit me down and remind me to breath. Afterwards the teacher's bass came out of it's bag, and the first mark ever on it was pointed out to me as well. I had to look a few times in order to see it. Your response is completely normal. It is great that you take good care of your instrument and while you will always hate marking it up, the next one won't hurt quite so bad.
As for the buzz, Michael's suggestion about the endpin is a good one. There are a bunch of other possibilities as well, which are easiest spotted when you can play and listen for where it is coming from and narrow it down. If it is in fact the bridge, then having a luthier who knows basses check it out is your best option. There are likely thousands of basses on this continent with adjusters that don't have problems, (they aren't as common in Europe, largely because the climate doesn't change as dramatically in places like France and England) so I wouldn't absolutely rule them out. They can be quite useful and necessary depending on your instrument and location. They can also be problematic if poorly installed. Make sure you go to a luthier who focuses on basses though, as a well cut bridge is one of the most important aspects in the playability and tone of your instrument. If you don't want adjusters that is an option, but hopefully one bad experience doesn't turn you off of them for good.