Not all basting sprays work well with polyester batting. Some quilters report having trouble using basting spray with poly batting; however, 505 does seem to work with polyester batting.
Ironing is not necessary when using basting spray, and probably not a good idea if the batting is polyester. Some quilters press the quilt sandwich after basting to compress it as much as possible, and it would be okay to do this with basting spray but certainly not necessary. Ironing is more common when basting with Elmer's glue, since it speeds up the drying of the glue.