If it happens that your purchased tracks cannot be found in Purchased Music tab (an issue by Apple), we suggest you create a Smart Playlist and set it to add only Purchased Music so you can see your purchased songs and confirm that the purchase is successful.
-advice from @Hoshipancake
Both Apple Music and iTunes are from Apple but they offer different services. Apple Music is for music streaming while iTunes is for purchase of tracks. While Apple Music contribute to the streaming charts (determined per region), iTunes contribute to digital album sales chart.
Yes, you can purchase the track and also stream on Apple Music. However, you have to <Delete from Library> the purchased track for your streams on Apple Music to count. Else the purchased track will be the one playing instead of the catalogued track on Apple Music.
Yes, you can. After you make the first purchase, delete the track or album from your Library first before logging in to your next account to purchase the same tracks/albums. Repeat the same process.
Remember: Only one (1) purchase per Apple ID counts. So make sure you're using a different Apple ID for your next purchases.
Yes, you may use the same card to purchase using 3 to 4 different Apple IDs. To do this, make sure that you choose "None" as the payment option upon SIGN UP. Only input your card details when you are making payment for the purchase of the tracks/albums.
Do not gift the tracks or albums. Gifting doesn't count on Billboard charts.
Buy the title tracks (and the rest of the tracks in the album if you can) within the first 24 hours after its release.
Yes, your streams will count. If you didn't use your free trial yet, please activate it only when nearing the comeback to be able to utilize it well.
Yes, just like in Spotify and Youtube Music, all offline streams will add to the stream count once you go online.