The big question is would they confiscate any other firearms that I may have?
Some places confiscate them all, leaving you ripe for retaliation by family, friends, fellow gang members etc of the criminal.
but in Los Angeles county where I live (no matter how clean) everything goes
Which makes LA a great place to run as a gang.
Anyone that stands up to someone's homie can be dealt with right after the police take all thier legaly held firearms.
when weapon(s) are taken, what is involved in getting them back once case is closed?
That depends on state law.
In CA for example a person must go through a background check, and they must pay a fee for that background check.
This happens even if the weapon is wrongfuly taken. If say an officer pulled you over, and confiscated a weapon legaly possessed, it would still require you to pay a fee and go through a background check to re-aquire later.
What would happen if you used the weapon to hold the intruder at gunpoint until the cops got there?
Check the law in your state. In many places you would be charged with kidnapping or illegal restraint. Having a gun does not afford you police powers.
It depends on the crime commited. Citizens have a history of actualy being the law enforcement in this nation for various felonies.
Some people (police) are just paid to do it full time.
A citizen's arrest can happen and a suspect can be lawfuly detained.
Unlike the police a private citizen has strict liability when performing arrests.
A lawful detainment in the process of a citizen's arrest can occur. You must research the law in your area on how citizen's arrests are performed and how they change for certain crimes.
Detainment is legal for various misdemeanors in many cases. Like you can hold a shoplifter till police arrive. Moving or searching them though could be illegal criminal action. Yet if the guy is a felon that just commited certain felonies what you can do can be significantly different.
The rules of self defense differ from what allows you to legaly arrest someone.
So in general it is usualy advised you do not arrest people, because while the law may say one thing, how it plays out to a jury at trial can be different.
If you legaly arrest someone that commited certain felonies, and you are then forced to use lethal force in self defense, a court may determine you actualy were illegaly punishing them and commiting murder rather than defending yourself.
So your actions being legal does not mean justice will prevail and the Court will believe you. That could cost you your freedom.
Since you are strictly liable in a citizens arrest, it also can make things more difficult in a civil case.
Also if the criminal is found not guilty or to not have commited the offense that made the actions valid and legal, then your arrest and actions performed could be determined to have been illegal.
Those legal actions in a citizen's arrest become serious crimes like kidnapping and battery if the arrest was not legal, and the arrest is often only legal if they commited the crime (determined by the court not you).
A citizen's arrest, and detainment should not be made lightly even in circumstances they are valid or legal.