New York State Education Department
NY State Ed has every bit of info for what you need.
I'm a retired teacher ( Western NY ) with many teaching and para friends still working, so -- from friends who still work I know that in the past 10 years, they have starting pushing aides into becoming "teacher assistants" -- meaning a 2 yr. degree. Also, many teachers with 4 year degrees and certification cannot find work and are taking those jobs. An "aide" (job description) is more likely to be office, cafeteria or library ( etc.)
The comment you make about being contracted and hired by an outside agency in PA sounds like the groups that work with troubled kids and families here. They do not hire people to work in schools all day with kids.