I think your questions are answered at http://www.ldraw.org/library/tracker/ref/policy/ . Generally other people should give you the chance to fix problems, unless three months have passed with no response. If you don't yet have the skills, and would like other users to improve your submission, please write something like "Anyone can make changes to this part" in the comments at submit time.
Chris
Chris
Chris (LDraw Parts Library Admin)