A website that doesn't bring new business to a company, it's a shame. Unfortunately even a great web developer may forget those requirements needed for a website to rank in Search Engines
It depends on the website, the market of my clients and amount of errors i've found. I usually process hundreds of checkpoints in order to identify potential issues, therefore the deliverable document may be longer than 30 pages.
Every business is unique and every report will reflect that uniqueness.
The report is usually written for ITs and Developers, therefore each anomaly is described in its entirety, including the repercussions on search engine.