After you apply the wash, make sure to clean up any places where you don't want the wash to go. As for hand varnishing, I suppose you can do that but I'm not sure if you can thin it with Pledge+water. Test it on a piece of sprue that's been painted to be sure.
Spraycans have been my choice for topcoating my minis and I haven't tried spraying a gloss before matte before. The way I see it, the Pledge in the paint will act like a gloss, so that's why I just spray matte right away.