https://squareup.com/compatibilityTap and Give runs in Android and needs Square POS App also running. Square POS requires Android OS 5.1 or higher, it also requires certain brands of phones and 1.0 MB Ram or more. For a list of Android device refer to https://squareup.com/compatibility   and make sure it is compatible with “Square for contactless and chip”

Purchases are made from the Tap And Give application by select Account. You will be redirected to Google Play where you can add the in app purchases. You can cancel your monthly subscription anytime.

No, Square does not allow the use of their terminal fully unattended, and if a card fails a person needs to press cancel on the phone or terminal.

You have to disable receipts and signature as per instructions, this is necessary to achieve continues transactions. Refer to configuration details.