Hello Southpaw07,
Thank you for using Apple Support Communities! I understand that you have some questions about downloading and playing songs with Apple Music. I would be happy to help provide clarification. When you download content to your iPhone to listen to offline, it would not use Wi-Fi or cellular data when playing.
The following support article provides more information about this process:
Add and download music, shows, and movies from the Apple Music catalog - Apple Support
This section specifically shows how to download content to play offline:
Before you can download content to listen to offline, you need to add it to your Library. Then, in the Music app on your iPhone, iPad, or iPod touch; in iTunes on your Mac or PC; or in the Apple Music app on your Android phone, find the item that you want to download, and follow these steps:
- On your iPhone, iPad, iPod touch, or Android phone: Tap Download
.
- On your Mac or PC: Click Download
.
You'll see 
when the download is complete.
If you have Automatic Downloads turned on, content automatically downloads to your device or computer when you add it to your Library. You won't see or .
Use the Watch app on your iPhone to add music to your Apple Watch.
You can download content on up to 10 devices. This content is accessible only when your Apple Music subscription is active.
Cheers!
