If seats have been pre-allocated and the aircraft is full, then it is less likely to be able to change seats at the check-in. If the plane is part-full or the airline uses an on-line seat choosing system (which many passengers don't use), then an early arrival would be the best tactic.
Economy, semi-flexible airline seats dates can be changed, and they are partially refundable on cancellation.
tough homework.
Yes. Either with the airline, or you make an agreement with another passenger.
Depends on how the airline has it configured, but 60-70 seats.
It depends on how many seats the airline wants in the aircraft for that class.
Yes, the airline is skybus (www.skybus.com). The first 10 seats are $10.
That you have a reserved seat or seats for a specific flight on a particular airline, departing at such and such time, etc etc.
You book these via the airline operator you are flying with
It differs from airline to airline but usually a very small percentage is first class.I would estimate anywhere between 20-25%.
A 320 has between 150-180 seats it depends on the airline and the configuration(s) they choose.Most of them are 180 seats,though You welcome
Fly Emirates
It depends on the configuration the operating airline is using. Between 450 and 800 seats, usually around 500.