No, the Samsung Galaxy Tab S6 LTE does not have the headphone jack and it only has the USB Type-C port for everything.
Check its look-
Check Full Device Specifications Samsung Galaxy Tab S6 LTE
Yes, Samsung Galaxy Tab S6 LTE does offer voice calling.
The device also supports a slot for 4G sim slot.However, the device lacks NFC ( Near Field Communication)
In the meantime , you can check all the detailed specifications and latest updates on this device here.