What is the use / advantage of WCF channel factory

1) we can create proxy of wcf at client pc to connect the web service but i saw people use some time wcf channel factory to connect wcf service from client application but i want to know why some one will use wcf channel factory instead of creating proxy at client pc?

2) please tell me few scenario when people use wcf channel factory ?

3) wcf channel factory provide any kind of security for web service ?

4) what is advantage of wcf channel factory ?

5) please tell me Client can use WCF channel factory to connect when mex endpoint & httpGetEnabled both are disabled at service end ?

thanks