DV does not use published air fares. They use Exception Fare earning chart to calculate mileage earn for the flight component. You can't breakout air fare taxes from other booking charges and taxes (which also don't earn MQD) because the air fare is not disclosed. But, as noted, if multiple passengers are on a res, each will earn flight MQDs based on Exception Fare chart and primary booker ony receives remaining package price MQDs after deducting taxes/fees and flight MQDs earned by all passengers on reservation.

"MQDs actually awarded will vary based on the final value of the Total Package Price, including but not limited to deductions for taxes, insurance, other booking charges, amounts paid directly to the hotel, car or activity provider, fees, and any element of the booking that is paid or reduced by vouchers or discount codes. All MQD calculations and awards are determined by Delta Vacations at its sole discretion and are subject to the terms and conditions of Delta Vacations. For full terms and conditions, please see Terms and Conditions tab below."

Yes, you will at least earn the MQD for the total package price minus mandatory taxes/fees when flying as a solo traveler on package. In some cases, the Exception Fare earnings formula for flights can exceed total package price (generally when flying in higher fare classes on longer flights with shorter stays in cheap hotels where hotel costs don't contribute much to package price). The below is for a 1 night package booked in C+ (20% of 6,820 miles is 1,384).