Yes, it supports Windows laptop with full function USB-C(Thunderbolt 3) port.
No, the ProBASE Gen2 supports HDMI monitor only.
The functions will work with iPad Pro, but ProBASE Gen2 required a USB-C power charger (like the 61W or 96W MacBook Pro’s charger) to provide power to the USB ports on it.
Yes, ProBASE Gen2 is compatible with MacBook Air 2018.
But, the MacBook Air’s USB-C charger is 30W which is “not” enough for “simultaneously” charging MacBook Pro and providing power to ProBASE’s USB and HDMI ports.
Yes, new Mac mini 2018 could fit underneath the ProBASE Gen2.
But it needs MacBook Pro’s USB-C power adaptor(61W/96W) for full PD function(provide power to USB and HDMI ports).
No, it is designed only for USB-C laptops.