You will need a lawyer for a current, correct and legal answer for the situation you describe.
You don't have to depend on someone else to protect you.
None. A gun in the home, or anywhere else for that matter, will not shoot you. If you are asking what are the odds of being shot by someone with a gun in your home, that's another question. You will have to be specific in what you are looking for. Is there a gun in the home already? Is it loaded or empty? Is it secured or not secured? Are you asking about being shot accidentally or during a crime in the home?
Lock the doors, have an alarm system, own a dog, own a gun,
You can not shoot anyone. Only in self defence if they have a gun.
You can purchase Cannon gun safes online from stores such as The Home Depot and Walmart. You can also purchase this safe online from retailers such as Amazon.
Most likely people have gun in there home for self defense
If they ask your permission and you grant it, absolutely.
For civilian firearms, they are usually marked on the gun. You will probably need to pay a gun shop a visit for some hands-on advice.
a squirt gun
Depends on whether you can legally have a gun where you live, and if the gun was theirs to give you.
No if the gun is not registered in your name , no you can not own a gun. if you do not have license to own a gun you can not have it either
No