I've hatched V. panoptes horni on both perlite and vermiculite. It doesn't matter which and certainly one is not going to make your eggs die. Inducing with meds may cause the eggs to fail though if it was too early for them to come out.
It's also possible that a few of the eggs are just nonviable and the rest are good. There's lots of scenarios.
You are not going to see the nominate V.g.gouldii in the U.S. in it's pure form from what I've seen. There are a few sources for fairly pure V.g.f. I believe. The Gould's are bigger like an Argus to slightly smaller normally. I can't speak for their temperment. V. gouldii flavirufus (to some V. flavirufus) are smaller desert forms of Gould's monitors. They are smaller in size as adults. My "flavi's" go after food just like an Argus, but are calmer in general when they don't smell mice.
"Flavi"

Adult male Argus

This is not my pic, so here's a link to a V. gouldii gouldii:
http://www.scienceinpublic.com/sciencenow/2004/2004_images/Chris%20images/Chris%20Varanus%20gouldii%20on%20a%20treadmill.JPG