excess earnings method

Hi,

I know that the excess earnings method requires us to divide something by a cap rate for intangible assets- but I feel like I’ve come across multiple applications of this concept and am thoroughly confused. Let’s say we are given information about a firms’ profitability (cash flows or earning or whatever we need)- what is a simple application of calculating excess earnings? Isn’t it only used for privates- why is that? And lastly does it get us the value of an entire firm or JUST the value of intangible assets or good will?

Thanks,

…and also an additional question- does an increase in other comprehensive flow through to retained earnings (ie does OCI increase retained earnings?

thanks