You want to minimize splashing. Some oxygen is good, but if it grabs any bacteria, well, bacteria love oxygen.
When you first put in yeast, it buds and reproduces until there is nothing left to keep it reproducing. You just shortened the amount of time it would take to build up. I was at a conference last week where they said the pros get a gallon fermenting so that they had enough yeast for their tanks.
Oooo, stay away from iron! Iron will turn cider bad colors. (yes, I know you were talking in metaphors)