AGC means automatic gain control. When enabled, it allows to increase sound volume.

It's easy. Just do not close program when you reboot/turn off your computer.

It's already done. You should use Notify remote party about recording option in order to specify your greeting message and enable answer a call in NNN seconds option

There is a bug in Modem Spy versions 1.7 and earlier. Solution: Keep caller ID window for NN seconds setting must be greater than Answer a call in NN seconds.
Also, check out if another application do not use modem at the moment. Modem Spy verion 2.0 beta 3 and later will show Call was accepred by another application status message to notify you about this problem. Automatic recording is not possible when that application is running.

Unfortunately, this is hardware problem. So, it can not be managed within software. You may try to replace your modem with another one

You will need to install special filter for your modem if you are using DSL. It should come with your DSL modem.

Yes, because Modem Spy is software. It can not be run on computer that is turned off. It even can not be run without computer.
