Sure, investment costs and fixed O&M are always specified per unit of capacity, and therefore the total (overnight) investment costs can be obtained by multiplying the unit investment cost by the capacity, and so on.

As I pointed out already, the capacity of your storage represents the maximum amount of energy that can be stored by the device. Hence, the capacity does not limit the level of the output flow in any other way, but only through the amount stored. A capacity of 1 MW translates into 31.536 TJ = 8.76 GWh, and so the output level could be as much as 8760×0.86 MW, if the full storage (8.76 GWh) would be discharged in one hour (discharge efficiency=0.86).

If you want that the capacity directly limits the output level, please model the capacity in terms of the nominal maximum output level, and not in terms of the maximum amount of energy stored. We have gone through illustrative examples before, for example the hydro pondage example, so there should be no need to explain all that again.

As I pointed out already, the capacity of your storage represents the maximum amount of energy that can be stored by the device. Hence, the capacity does not limit the level of the output flow in any other way, but only through the amount stored. A capacity of 1 MW translates into 31.536 TJ = 8.76 GWh, and so the output level could be as much as 8760×0.86 MW, if the full storage (8.76 GWh) would be discharged in one hour (discharge efficiency=0.86).

If you want that the capacity directly limits the output level, please model the capacity in terms of the nominal maximum output level, and not in terms of the maximum amount of energy stored. We have gone through illustrative examples before, for example the hydro pondage example, so there should be no need to explain all that again.