If you have your friends test read or edit a book for you,
it's best to not give them a deadline on finishing it. Most people have
extremely busy lives, so if you want quick feedback on your story or a fast
editing job, you're better off hiring someone for the task.
When you ask your friends for feedback, be aware that they won't want to hurt your feelings, so they'll probably be vague in their critique, and you'll have to analyze their comments in order to interpret what they are saying. For instance, two friends said the same thing about one of my novels "the second half of the book was a much faster read than the first half". This told me that the first half of the book needed a serious revision. I added more action and ruthlessly cut fourteen pages using rewording and deletions in order to try and balance out how fast it read and was told that it greatly improved the book.
Some people think a single edit of their finished novel is sufficient. However, the writer is too close to the story and will not notice that they've repeated information two or three times that they wanted to make sure was included in the novel. I suggest after the first edit that you read the book aloud to yourself or someone else, because it will bring to your attention things that you've already covered in your story, and in addition will highlight awkward passages that you need to edit so they are easier to read.
There is no substitute for a spell checker, but it's not an absolute. There are many sound alike words that people misuse, including simple words such as "there", "they're", and "their", and if you have trouble remembering which is which, you should expect to pay a premium for editing services.
Keep in mind that even if you have professional editors working on your novel, they're human and will miss things. One writer blogged about how many people he has editing his work and test reading it, and yet I found mistakes in the first chapters of both of his novels that I read (both wrong words), so you have to keep in mind a spell checker won't tell you you've used the wrong word if it's spelled correctly, and having multiple people edit your work won't catch all the errors. You just have to decide how many times someone examines your work with a critical eye before you declare it finished and be ready for the comments of others when they find things that everyone else missed.
