When I was active duty, we did the Taj Mahal in one day from New Dehli via a contracted bus. I would highly discourage you from taking the bus.
The General and his staff took the train. You should be able to find express trains that get you there and back in a few hours.
I've never flown Kingfisher. However, whatever you do, bring lots of Pepto, your own toilet paper, and safe food and water. Do not trust the bottled water there because they reuse the bottles, fill them with local water which will make you sick, and then put a new twist off top on them without your knowledge.
