1) Score study. After you finish the great orchestration books, the primary source of further study is always the works of great composers.
2) Form in Tonal Music by Douglass Green is good for this purpose, although it's not comprehensive. Perhaps what you're really looking for is something like the Anthology for Musical Analysis by Burkhart & Rothstein.
Sorry about the prices of those books on form. That's pretty typical for forms & analysis books since they're primarily text books.