(Non-surface-finished top sides of ceilings, underlay concrete and concrete floors) does this also mean the floor slab here?
Top side means that the surface on top is meant. So as in height, not as flat and perpendicular in the floor plan. The floor slab is not surface finished on the top side in terms of the "top edge of the raw floor," i.e., no screed has been applied yet to even out the irregularities. In this state, up to 25 mm unevenness is allowed at a measuring point distance of 10 m. Height, mind you.
I have the shell construction drawings here; does this mean the execution plan? Otherwise I have nothing.
Formwork plans are derived from execution plans of the floor plans. Execution drawings are in scale 1:50 (for details sometimes even larger) and already specify details such as where which light switch is located, where which ceiling panels rest, which fire resistance class certain doors must have, etcetera.
Floor slabs are never precisely millimeter-accurate under houses; masons are not watchmakers.