This question is only a sprigboard for discussion and debate and cannot be asnwered definitively on this venue. For debate and discussion of the pros and cons it is STRONGLY suggested that you post this question one or more of the many blogs or chatrooms that concerns themselves with this topic.
They debate, revise, and adopt proposals for laws that establish policy.
Literally, tens if not hundreds of thousands of laws. My copy of US state gun laws is about 2 inches thick. It is estimated that there are more than 20,000 gun laws in the US- and you are asking about "around the world".
US obviously because of gun crime they should put more laws on guns duuh
It's arguable that the current gun control laws in the US are stretching the constitution to the breaking point. Anything much stricter and it would be impossible to maintain the fiction that they're compatible with the 2nd amendment.
Chicago and Washington DC in the US
Your question calls for an opinion. My opinion is that most gun laws are useless. There are several thousand gun laws on the books NOW in the US. Many of them make little or no sense.
Depends on the laws where you are. You did not tell us where you are.
Laws of all types get updated every year.
Depends on the parts, and from what country. The frame (receiver) of a gun is subject to import laws.
Depends on which laws. The US Congress is in charge of Federal laws, and the State legislature in in charge of State laws.
Firearm laws are too complex to give you a simple answer. In MOST of the US, there IS no gun registration. What you can and cannot do depends on the laws of the place where you are. Laws vary a lot from place to place.
Provided you follow the laws, yes.