For navigation, yes helmet mount is the way to go with traditional night vision whether PVS14 or dual tube goggle. The strength of traditional Night Vision is in the navigation end more than for scanning for animals. Thermal is much better at detection and that is what scanning is often about. If you are scanning with traditional night vision and shooting with thermal, you will miss a lot of animals that you didn't know are there, but you will navigate well getting there. Some will run a helmet with thermal on one side and a PVS14 on the other. Most will say they won't run them at the same time while there are those that say they can and it doesn't bother them as far as headaches, etc. A person could also run fusion with something like an e-COTI or TAD along with their night vision. Super cool, but thermal detection is still very limited. Great for close range stuff, but not if you need to detect a hog or coyote at 1000 yards, etc.
As for thermal scanners, many like to go hands-free. I personally like a handheld thermal scanner, but it really depends on how it will be used.