Feng's main space control tool is iWS1 out of his command dash. This mid is i13 (more like i18 with input time), has great range and is only -1 on block. On hit, it's +5. Fairly fast whiff recovery, and extremely variable spacing. Based on seeing your opponent whiff or dash in, you can try to confirm iWS1-2 for 26 damage off it. This move is extremely low risk, and mixes up QCF1 if done more slowly.
QCF1 is a low shoulder that cannot be low parried. It's -14 and deals 23 damage. On hit, this has considerable pushback, resetting to neutral. This is a high crush that can often evade mids, and a scary counter hit launcher.
The command dash these moves come from is a high crush if you hold DF during it.