Editorial services? When publishing a book, what is the Editors job?

It depends. There are different types of editors. There are those that do editing for grammar, fact checking, and those that suggest storyline changes. THe ones that suggest storyline changes. Editing for storyline changes (can't remember the official terminology) is the most expensive type of editing. If you want all types of editing, it can run you upwards of $1,000 if you hire a quality editing service, and you certainly don't want just anyone editing your book, so make sure that person has experience and verifiable proof that they can do the job, and it's even better if any books they've edited any commercially published books (not self-published).