German Brewing

Why do you want to do that as a home brewer? What do you gain from Drauflassen? Can you do a second brew 3 days later and guarantee that the new wort you pitch on top is at the right temperature?

Drauflassen only makes sense when you make larger batches and at regular intervals.

Yes. Effectively the fermenter becomes a starter. There are a few restrictions though, one should not do it too often (3 times) otherwise there will be a noticeable quality drop. The other one is more important: you need to pitch the wort at the right lager temperature (can you do that?) and when the yeast is at peak log phase (again, are you sure you can do another brew timely enough?)

Temp is no problem with small batches since it's pretty easy to chill down a couple gallons in an ice bath.

Timing wise, I dunno how precise it is but last time I pitched after 2 days and the first batch appeared to be at high krausen.

Today the weather is nice so I'm brewing a full size batch outside. Going to try out the yeast 02 scavenge instead of pre-boiling.