Can you tell me about some books that focus on how to build affirmations + autosuggestions,how to say them, how long to say them, the best way to say them, ect.

There's one book by guy called Noah St. John called The Secret Code of Success, in which he talks about wording affirmations in question form (he calls them 'afformations')and why he thinks this is a better way to state affirmations. You could check it out, it's quite detailed.