1 - Pre-Patch Windmill Punch into Dragon's Wrath does not hit Sub-Zero's regular Slide and EX Slide because Dragon's Roar hitbox and Dragon's Wrath hitbox are small. [FIXED in MKXL]
2 - Pre-Patch Windmill Punch into Shaolin-Ferno is safe against Sub-Zero's Frost Bomb. [Same thing]
3 - Pre-Patch Windmill Flurry is safe against Sub-Zero's Frost Bomb and Kung Lao's Cyclone. [Same thing]
4 - Pre-Patch Windmill Flurry into Shaolin-Ferno is safe. [Same thing]
There is no major stealth buff for Flame Fist Liu Kang.