Maybe.
This is a complicated question. You should get the legal records for the area, and speak with an attorney in the area. This question likely involves questions of adverse possession, that is detail specific.
If the fence is on the legal, surveyed property line, then the line is official immediately.If the fence is not on the legal, surveyed property line, your state's doctrine of mutual acquiescence will determine if and when the fence will become the line. A real estate attorney in your area will be able to tell if you have a legitimate mutual acquiescence claim.
They can nail into your fence but if they violate your property line you have grounds for legal action and you will win.
Maybe. If your state has the legal doctrine of adverse possession and/or mutual acquiescence, then the fence may be the legal property line. I suggest you talk with a real estate attorney in your area for information specific to your state's laws and your specific situation.
The legal age to own real estate in Illinois is 18 years old. Minors can own real estate in Illinois, but it is often held in a trust or through a guardian until they reach the age of majority.
tear it down if its on your property
You have to be 18 to have any real assets to your name.
You would need the permission of the owner of the property where you are doing so.
Yes, but you cannot own property without being emancipated.
Legal understanding is a hypothesis or method of felt that clarifies how the legal ought to decipher the law, especially established reports and enactment.
yes he is legal owner of property
Depends on who owns the fence, i.e. whose property it is on or who bought it in the first place. Often one person installs a fence (maybe 3 owners ago) then allows the neighbor to install wood on their side of the owners fence. This wood is the owners wood but people do it cause it is cheaper than installing a second fence on their own property. If you own the fence (its on your property) then you can do whatever you want including tear it down. If it is on their property they can tell you what you can or can't do. The best thing is to go to the neighbor and actually talk with them about what you'd like to do.
Yes, they are legal in the state of Illinois.