You and your wife have had a bad experience - it does happen.
There could be many reasons for the attitude of the cabin crew member - could have been forced to do extra sectors despite many long delays throughout the day - different crew members react differently to these situations. She could have been leant on heavily to accept an unscheduled night stop when she was expecting to spend the night out with her boyfriend/mates..who knows..? But it is unprofessional and shouldn't happen.
As far as the piloting/serviceabilty of the aircraft aspects are concerned it is quite normal to 'take it on the roll' - as long as the speed/angle of the turn is not too high. The apu is not required for a safe flight - quite normal to fly w/o one - just makes the start a bit more involved - no big deal and certainly not an indication of a poorly serviced a/c - unless it happens a lot...
The crew are very often presented with drunk pax who have been allowed to board by the gate staff and as was said above, it's quicker to carry on rather than offload at this stage.
The very cheap fares are possible these days because the crew are squeezed hard on time and meal breaks so at least you don't have to pay a fortune AND have a bad flight.
I'm sorry that the trip wasn't good - you should write to the customer service dept - if they don't know about it they can't do anything.