Herzlich Willkommen!
Nope, it’s all at once. You have the HF part where you can store data in it, to be read by NFC smartphones, or to trigger events if you have the right tools on your phone. Not sure about copying the LF ID though.
You can scan it to login to your computer with the right reader like the KBR1.
Did you read this very informative thread?
For payment, since you seem to be based in Germany, Walletmor is an option for you.
You can have several implants in the same hands, they just need to be implanted with sufficient space between them. Check the Implant Sutra - An index of implant positions that have been discussed and/or tried
Digiwell carries several DT items in the online store and they’re located in Germany.