Hi, thank you for using health care magic.
I can understand your concern.
Masturbation practice does not affect any organ of body.
Masturbation is quiet common practice in male and till date no ill effect have been reported. But on the contrary lots of myths surrounding masturbation is present in society.
Secondly you reported curved penis , but variation in penis size and shape has been seen , so if you are able to insert in vagina properly than no need to worry.
Ejaculating early is also subjective thing , if you are able to give pleasure to your partner with time you have then it all maters. If you are not able to do so then using condom, practicing start and stop , squeeze technique will help to last longer.
Hope this will help you.
Regards.

Hello Welcome to HCM

Masturbation is manual stimulation of genitals in order to achieve gratification. It is completely a safe practice and it don't cause harm in terms of potency and fertility. It don't affect kidney stones.
You have also mentioned the problem of early ejaculation which can occur due to anxiety and hyper excitement. Consult a Psychiatrist if the problem is causing effects in your marital or sexual life. Medicines like SSRIs are used to delay ejaculation.
Slight curve is considered as normal in erected penis and there is no need to think and worry about this thing again and again. Consult a surgeon if the curvature is causing pain or difficulty in penetration. If the problem is not severe be assured that you are perfectly normal.

Thanks