As far as I know, the software is shipped with the device and is considered a part of the purchase. Perhaps that has changed in more recent years, so please keep us updated on the response.
The frame grabber isn't required to use USB3 Vision with IMAQdx -- it just is an option for people who potentially don't have USB3 ports on their PC, or perhaps the ones they have don't have a reliable chipset/driver, or maybe they want more ports than are available, etc. Since not all chipsets work equally well for the machine vision use-case and provide enough bandwidth for multiple ports to stream data, purchasing the 8242 helps people get started with a known good hardware setup so there are fewer things to worry about when getting a system up and running.
There is nothing different about plugging a device in through the 8242 vs. any other USB3 port on the system from an API perspective -- the 8242 advantage is really just the guarantee of enough power/bandwidth and quality hardware/driver stack to work with. Whether you're using the IMAQdx API or a camera vendor API to communicate with the camera, you should be able to do so from any USB3 port on a machine.
