Extensions.conf general questions

I am completely lost in the extensions.conf file. I have a few questions:
1. I am using the auto-generated extensions.conf installed with vicidialnow 1.0.1 and alot of the information in the conf file is for T1 and IAx lines and they are not commented out by default. I have commented all of the ones that I think are not for me. Should I leave all the uncommented items alone from a new installation or completely customize the file for my purposes?
2. Where can I get an in depth tutorial about what the extensions.conf file is all about?
Thanks
1. I am using the auto-generated extensions.conf installed with vicidialnow 1.0.1 and alot of the information in the conf file is for T1 and IAx lines and they are not commented out by default. I have commented all of the ones that I think are not for me. Should I leave all the uncommented items alone from a new installation or completely customize the file for my purposes?
2. Where can I get an in depth tutorial about what the extensions.conf file is all about?
Thanks