What kind of metrical line does Dekker use in The Honest Whore? Can it be used in the same way as in Shakespeare (iambic pentameter) to understand the meaning and the pronunciation of the text? Thanks.

Dekker was writing at the same time as Shakespeare, his plays being produced for similar purposes and audiences. As such, it is unsurprising that his techniques and styles can be compared to Shakespeare's. Like Shakespeare, Dekker uses iambic pentameter—sometimes strictly, and sometimes more loosely. More frequently, however, he seems to rely on iambic tetrameter (where there are four beats in a line, rather than five). His dialogue is written mainly in free verse.
Let's look at an example from the first scene of the play:

Kinsmen and friends, take from your manly sides [iambic pentameter] Your weapons to keep back the desp'rate boy [tetrameter]From doing violence to the innocent dead [tetrameter]

In a play that uses strict iambic pentameter—which simply means that the line has five "feet," or points of emphasis—we can use this to help us interpret where a speaker of early modern English might have placed emphasis on certain words, although we cannot be too prescriptive about this. Iambic pentameter can be fluid, and the place our modern minds might expect an emphasis to fall might not be the exact place an Elizabethan speaker might have put it. The difficulty with a play that moves between tetrameter and pentameter is that it is harder to understand the intent of the original writer. A modern speaker might attempt to wrangle a line into tetrameter where it would originally have been emphasized as pentameter.