Not normally once semen production has started it will keep on producing into old age.
If someone has told you that goat semen helps you to lose weight I think that they are seriously pulling your leg. The only that semen can be associated with weight loss in any way would be because of the exercise that it takes to produce it. Semen is protein and therefore it is a source of calories if consumed. There is no semen in the world that will help you to lose weight by wearing it.
All child support ends when you lose legal custody of the kid, or if the kid turns eighteen.
After all there is no harm in swallowing your partners semen.
You produce semen all of your life.
No semen does not cause any body pain at all.
Exercise
No.
Yes but why would you want to.
A toy bear
Semen is free. It's all protein! Eat as much as you want.
Yes but some time will have to pass before you can do it again
Typically, yes. Kid's metabolisms are much more faster than adults' are. However, unless a child is very overweight, it's generally not recommended they try to lose weight until they're in their late teens or early 20's.