I've been thinking about this angle for a while. Geocaching is one of my main hobbies.

The Delphi Highbridge cache was placed in 2010. I know you weren't asking if that cache was a 'lure', but I wanted to add that bit of insight.

Yes, there are several websites to geocache. Do we know which site the girls used? I will say that most cachers use the official geocaching platform, Geocaching.com. I would actually be surprised if they were using something different. Another bit of info is that Geocaching.com has a free level and a subscription level which unlocks more cachers for users. The Highbridge cache is accessible on the free level. Do we know if the girls had a paid subscription?

B. The vetting process for caches is fairly strict. Volunteers don't always physically go to check out the cache but they do thoroughly vet each cache and location. A geocache CAN be on private property if permission is given. I will say that I've never gone caching in a cemetery and getting permission for that would be highly unusual. I do live in a different part of the country so maybe it's different in Indiana.