It seems I have to use snetcfg.exe in order to make a silent install, right ?
Yes, that's right.
In the mail I received, it is said I can send you new names for drivers and devices and information to include in the resource.What exactly can be changed, and where will I see it ? I mean, I don't know exactly what I can custom.
It supposed that you provide the new name for driver binaries instead NDISRD (ndisrd.sys/ndisrd.vxd) used for the standard build. And any copyright/product name information you would like to include into the binaries resource.
By devices, does it mean that you can change the name of VirtNet adapter for us, or will we have to do it thank to its source code ?
We don't customize VirtNet and you can do it yourself when needed. By the way, in order to get the source code for VirtNet please send a request to support(at)ntkernel.com along with your Plimus order ID.