Best PDF editor around is BlueBeam Revu. It'll let you open the application PDF and type away, check boxes, add signatures, etc.

I've tested many, MANY such programs over the years and BlueBeam is far beyond its competition.

And... you'll likely get your app done well within the 30-day trial period.

Dandy
(No affiliation, just an impressed customer.)
http://www.bluebeam.com/web07/us/downloads/standard/

Being offended is a natural consequence of leaving the house. - Fran Lebowitz