TW Raven Owners: Set Up Questions

From all reports.....a Minus K is good for all turntables.

AC-3 weighs 55 Kg with 3 armboard but no arms.......according to Thomas.

It's hard to beat a wall-hung shelf (especially if mounted on a masonry wall) for reducing the effects of structure-borne feedback?

My apartment has solid concrete floor with tension
cable runnig through them.

This is called a
'prestressed' concrete floor and is designed to allow greater spans between
supports, with thinner floor thicknesses.
It is achieved by reducing the amount of steel reinforcing in the slab and
substituting steel cables (within permanent sleeves) which then are post-
tensioned.......after the concrete has initially cured.
It essentially pre-cambers the concrete slab so that the 'dead load' brings it
back to horizontal.
These slabs are becoming more like 'membranes' and because of the spans
they allow.....can actually bounce?
With the right equipment one can hear the structure 'singing' or 'moaning'?
They are possibly the worst type of floors on which to mount audio
equipment....particularly turntables?
If the outer brick wall is non-load bearing.....it must be supported either on
the floor itself or a concrete beam structure spanning between supporting
columns?
If the latter.....it is less prone to movement than the prestressed floor and
fixing a wall-mount shelf to it (as close to a column as possible)....will be
preferable.

30cm is quite thick for a concrete slab.....especially a prestressed one. How do you know this fact?
The load carrying capacity of any floor has little to do with with it's BEHAVIOR under dead loads, live loads and impact loads. 400 Kg/m2 is not so great considering that 4 hefty men each weighing 100Kg can stand on a floor area not much more than this?
A trampoline can certainly support this load also but I would be loathe to locate my turntable on one?

The 'centring' issue is not a problem if you use a top-plate supported on 4 equally placed 'spacers' over the Minus K stand.
I have checked this directly with Minus K and it's something they recommend.
Just take into account the weight of the top-plate?

Most turntables (and also audio equipment) are usually supported on either three or four legs so the weight is not evenly distributed over the top of the Minus K stand. It is distributed over three or four POINT loads.
Minus K simply advises that the overall load is placed generally around the centre of their top-plate. Even with my nude Victor DD turntable which weighs 10Kg surrounded by 3 armpods each weighing 12 Kg.......Minus K are happy that the arrangement is CENTRED on the top-plate. In other words.....the load does NOT have to be uniformly distributed.
However I would be happier to add my own top-plate ex butchers block or slate and support it on four neoprene or slate packers on top of the Minus K top-plate.
This would distribute all the loads evenly onto the four 'packers' which would be CENTRED over the Minus K top-plate.