This is most likely because the separate string you used before cutting (used to tie the loops) was not tied tightly. It’s a good idea to tie it as tightly as you can and make at least two or three knots.
Very low-cut pants don't stay up very well. Your hips are the widest part of your body, so pants need to be relatively tight to stay up. This "tight" area...
It depends. If your instrument is in good shape and the neck is not bent out of shape, you don't need to replace them very often. Depending on how much...