The Town of Wallkill Police Department maintains records of persons who live in the Town of Wallkill, and are registered sex offenders. These records are maintained by the detectives.
99 Tower Drive
You may find answers to many of your questions by visiting the New York State Division of Criminal Justice Services website.
Below is a link to an additional sex offender notification service/website. Besides being able to register for an email alert notification when new offenders move near you, it also has a mapping feature that shows local offenders' locations.
Please note it is not a NYS website, please read their disclaimer.