Vitamin E will help your skin, but I can’t see that it would do anything for a curve. Use the search button at the top of the page and enter "fix curve" and you’ll get about 30 threads on curves.
Girth exercises, except normal jelqing, are considered advanced moves and you should just do the basic workout for at least a month before you try the more extreme ones. Increasing base girth is a particularly tough problem. Have you read this thread?
A Quickstart Guide to Manual Exercises
It has information about girth exercises and lots of other things. You should read all of the threads listed in this post before you do any PE work. You’ll save yourself a lot of trouble.