Hello MicheleChilli,
Thank you for reaching out in Apple Support Communities. I understand you have some questions about the Apple Watch GPS vs. Cellular. I can help with this. With the GPS version, the phone needs to be within Bluetooth range to get any notifications sent to the watch or be connected to a nearby Wi-Fi network. This is how they communicate with each other. The Cellular version doesn't need to stay connected to the iPhone in order for it to operate independently, it uses it's own cellular data connection. Find My iPhone will work on both, but the GPS version will need to be close enough to the iPhone or connected to Wi-Fi, while the Cellular version does not.
How to use your Apple Watch without your iPhone nearby - Apple Support
Hope this helps.