I would recommend using DME not from the recipe to make your starter. Yes, it was going into the recipe anyways, but you're also adding extra water when you make the starter. Unless you account for that when you fill your fermenter, you'll be slightly cutting your gravity by adding the starter.
As for pitching, I've had plenty of success pitching a 1 liter starter in it's entirety. Give it about 12-18 hours of a head start, pitch to the wort and you'll have healthy, active fermentation very soon.
Just my 2 cents