Solar power plant cost

I have been wondering on few related things:
1. When I want to setup power plant, what are all the things I need to procure?
(mounting hardware, trackers, Wiring, circuit breakers, solar inverters, Batteries, Solar Panels, Real Estate to host the panels - how many on an average for 1MW)? What is the cost split up (on average)
2. Expected level of spare parts?
3. Any software (inventory or plant monitoring software)? If so, what would be cost of software?

4. What is the cost of operation?
5. In India, the rate for 1 KWh is about Rs. 15/-. What makes it so much? (of course there is a huge one time investment which needs to be recovered). But, what is the interest rate and payback period for which this rate is calculated?
6. I want to install a rooftop panel - What is the likely payback period?

There are two components to a solar power plant cost. Module price and the rest of it classified under balance of system (BOS). Module prices are around $1.5-1.8/W for thin film and around $1.7-2/W for c-Si. There are some reports of c-Si selling around $1.5/W (below cost) in strategic moves to capture markets. Range of price is for efficiency variations. Balance of system consists of inverters, cables, mounting structure. For a large solar farm (and not residential rooftops), it hovers around $2/W, but can be brought down to $1.5/W.

Total installed cost of around $3/W. Thin film will be a lower cost solution for solar farms as you are not constrained by area like a residential rooftop.