The puffy face is likely to be candida-related (candida can cause 101 different symptoms) but it isn't something I have heard of.
>Even though Sugar isn't listed on the ingredients it does contain sugar. Is this from the lactose?
>I want to make my own yogurt and bought a yogurt maker today. Can I use store bought organic plain yogurt as a starter?
yes, but the best yoghurt (both for taste and bacteria) is when you use a (good) probiotic capsule as a starter.
>Does the process kill any sugars?
Yes - this is the whole idea of fermentation. The (good) bacteria eat the sugars in yoghurt (lactose) and turn it into lactic acid. That is why good strong yoghurt should taste sour (acidic) - not sweet. If it is sweet it has too much sugar.