Welcome to HCM.
Most of the problems mentioned by you is not abnormal.
1. Masturbation is not injurious, rather healthier.
2. Pre-ejaculatory fluid is a gift for you. It is not related to semen. It is mucus secretion from urethra
to coat the urethra to protect the sperms during ejaculation from an acidic environment.
3. Few drops of urine dribble after urination is also common for everybody. You have to shake well your penis after the act of urination so that further drops will not dribble.
Very rarely if you have constipation
and when you strain for stools, few drops of prostatic secretion may likely to come while defecation. If you overcome your constipation ,this problem also will be solved.
Nothing to worry.