kWh is stored energy (SBR096 = 9.6 kWh usable). kW is how hard the hybrid may charge and discharge (SH10RT-20: 10.6 kW / 10.6 kW). Both sit in that pairing's datasheet.

On SHRT-20 an SBR stack whose operating voltage sits in 150-600 V, so from three modules (SBR096). SBH 5.0 kWh modules are the other Sungrow line. A Dyness Tower or Hoymiles LB does not belong behind it.

On Dyness Tower yes: the BDU is its own article (Tower BDU, S3 or Pro). Sungrow SBR has no separate BDU; modules click plug-and-play with no cables between packs. SBR064 ships with an empty dummy module.

Not until the trade account is approved. Capacity, datasheet and whether the article is make-to-order (amber traffic light) are public.