This is quite a large question, so I will focus on one of the deceptions and how it is finally resolved. The centerpiece of deception in the main plot is the mistaking of Hero's gentlewoman, Margaret, for Hero by Claudio and Don Pedro. This enactment upon Hero's balcony of a tryst (between Margaret, supposed Hero and Borrachio) is witnessed by by Claudio and Don Pedro and instigated by Don John. The theatrical device to mention here is that there is no indication in the script that this scene is actually played out before the audience, though performances sometimes include it. In the script, it is only recounted by Borrachio to Conrad.
This central deception is carried one step further, when Claudio plans to deceive Hero by showing up to marry her, but to turn on her just before saying his vows and accuse her of not being a virgin and deceiving him with a lover on her balcony.
This causes Hero to faint, who, with the help of her father, Friar Francis, and Beatrice, decides to deceive Claudio by pretending to be dead.
Once the truth is unearthed and Hero is proved innocent, Claudio agrees to marry a niece of Leonato's (Hero's father), and is shown three masked women before the true Hero is revealed and all is well. A final deception, the fake "neice," that leads to the resolution.
And it is always worth "noting" that in Shakespeare's day the word Nothing (from the play's title) would have sounded very similar to the word noting, making the play also one that is "much ado about" what one is able to note or see.