Didn't really follow that formula, but here's my advice:
1) Thick mash means scooping or straining out the malt, with enough wort to cover. After you've done a few of these, you'll start figuring out the appropriate amount of liquor to malt, but at first, leave the decoction a little thinner so it's harder to scorch. You'll also boil off a bit so give yourself some room for error the first time.You won't get quite as much Malliards, but that's not an issue in a pilsner. Just scoop out the malt and top up with wort so it's barely covered.
2) Regarding the quantity, here's a simple trick. One quart of thick mash per pound of grist. That simple. The BeerSmith calculator and similar formulas are very precise, but they come in under for many people as the mash cools down during the transfer. The most frustrating problem with a decoction is coming in under temperature and having to pull more or do a "mashout" of sorts, which throws off your sparge volume, etc. You'll probably only need 75% of that quantity, but pulling extra ensures less work. Just gradually add it back as it cools. My stovetop system has horrendous heat efficiency so I end up using almost the entire volume. Work with that simple guideline initially, you'll thank me later. And use this rule for any 20-30 F jump.. If it's only a 10 F, you could pull half a quart a pound.