Kiyomaro's power and toughness don't affect whether it has vigilance or the life-gain ability.
2005-06-01 • wotc
Losing vigilance after attackers are declared doesn't cause Kiyomaro to tap.
2005-06-01 • wotc
If you have seven or more cards in hand when Kiyomaro's triggered ability goes on the stack but less than seven when the ability resolves, the ability does nothing.