I couldn't figure it out myself (tested with large grids, see below) and dug through his responses:

引用自 DraygoKorvan：

[on why a flat surfaced wing creates lift:]
@drchocolate its called deflection drag, by exposing a broader area you create a dragvector perpendicular to the surface of your craft "lifting" it. To save on a lot of cpu the mod only calculates down to 1x1x1 sections. The default setting does calculate based on ship shape but only for drag and deflection drag.

引用自 DraygoKorvan：

[is there a way to disable flight?:]
The floatyness comes from the deflection drag, you can lower or eliminate that to change the floatyness.

引用自 DraygoKorvan：

Advlift calculates the point where physics is applied and uses that instead of the center of mass.

And the reason for my fruitless research :D

引用自 DraygoKorvan：

There is no deflection drag for large grids.

It's a multiplier for the upwards force, when you slightly pitch a fast moving surface upwards.
Would appreciate himself explaining the settings a bit more thorough, but i take what i get^^
Hope this helps. Atleast I know where to look the next time I forget this again