My random thoughts:
Munich Helles:
Watch boil pH - you want a lower boil pH to give smoother hop bitterness (see Kai’s (Braukaiser) site about this). I’ve tried working with lower boil pH with Helles to good effect, takes the rough hop edges off.
+1 to Weyermann Acidulated malt (and Lactic acid). It does add that certain je ne sais quoi.
+1 to 7-15% light Munich or Vienna in the grain bill
Hallertau-derived hops. Maybe Perle. Not so hot on German Northern Brewer for Helles. You just want light supporting hoppiness with slight floral note…if anything.
After farting around with trying to get more floral hop aroma, I’ve found that Jamil’s single 60 minute addition of low AA Hallertau is right on. Late additions leave a bitter aftertaste after a cold, medium-long lagering period.
German Pilsner:
Try 7% or so Carahell, the rest Pilsner (German) malt, pH adjusted with acidulated.
Carahell adds a nice graininess that compliments the spicy hops (lean towards Tettnang/Saaz). Some folks (including Victory) like Spalt, I haven’t had much success with it in my recipes.
I’m finding I don’t like Carahell in a Helles, light Munich or Vienna should give just the right character and better grainy sweetness.
Carahell gives a bracing maltiness to a Pilsner, despite being a crystal (10) malt. It’s grainy, not sweet, to me.
I don’t think Melanoidin malt is necessary in a Helles or Pilsner.
I generally haven’t seen the need to add Carapils/Carafoam. Good mash, strong boil, clear wort, good ferment and clean, cold lagering yields plenty plenty plenty of head.
Yeast: go for a starter! I build up a 3 gallon starter from a vial to boost up yeast count and to get enough yeast to work with. Once a strain is built up, I repitch yeast (from lower OG beers) and make sure I have enough on hand.
Overall, when brewing light German beers, you can’t be too precise. Get a pH meter, know your water, have excellent/precise temp control, pitch cold, at least loosely monitor yeast counts (have plenty of yeast on hand and at try to at least visually watch slurry density and overall volume). Pitch cold, hold at 48F or so, don’t bother with a diacetyl rest (you don’t need it, you used enough yeast and kept cool temps, long enough, right?).
All grain, crush your own grain right before you brew. Use only German malts. Give it time to lager, you will be rewarded. Acidulated and Lactic acid have their places at the right times (mash vs boil) and once you dial your process in, you probably won’t need straight acid as much (depending on water of course). Use only German malts. I’m married to a German. Making things like a German does is a lifestyle and philosophy for living and is as much about process as ingredients. Take all of August off every year (and brew if you want). Work smart and finish at 5 every day. Once you’re done brewing your precisely brewed German lager…which you completed on schedule, enjoy a liter or two of your previous one, while eating a home made lye-dipped pretzel (and don’t skimp on the lye). Oh, and use only German malts…and hops.
Prost! 
