Yes, that’s what they do, it’s called a levelized cost. These costs usually come with a sensitivity analysis of the impact of the different assumptions.

Wind or solar is actually often commissioned using a power purchase agreement for a certain price per kWh, guaranteed over a certain period.

Unless the wind turbines are trapped in some sort of time freezing status field, I would generally assume that they both can be measured in megawatt-hours. Or you can multiply out by 3.6 to get to gigajoules if you want more sensible units to play with.