Maybe I missed this in an earlier lesson - do I pronounce this as machung-wa, or do I actually pronounce the g?
You pronounce the "g". There's a difference between ng and ng':
ng as in "finger" (pronounce the "g")
ng' as in "singer" (don't pronounce the "g")
So this word is kind of like "mah-CHOONG-gwah", or in IPA [ma.ˈt͡ʃu.ŋgwa].