Packet Writing allows for drag and drop. I'm not familar with InCD but Roxio's version there is no formatting of the disk that has to be done manually, you drag and drop and it does its thing.
As far as DVDShrink not seeing the disk in the drive, well I don't know, but that shouldn't have anything to do with packet writing.
By DVDShrink not seeing a disk in the drive do you mean not seeing the retail DVD when its inserted? If that is the case does it show up in Windows? Try exiting DVDShrink, then putting in the disk and waiting for Windows to see it, then re-open DVDShrink, I've had that happen to me before.
For simple burning maybe you should just drag and drop from within Windows without Nero, and then click in the left column of the window on Write these Files to CD.