Question about Draining Health
Yes and no.
It depends on the source of the life steal.
http://wiki.guildwars2.com/wiki/Life_stealing
what class are you talking about? I would head over to the necro forums (assuming you are talking about necros). They can provide you a more detailed answer.
But as a brief answer, yes most of the syphoning skills are effected by healing power, but the scaling is so pathetic that no necro could possible justify it. Basically with 0 healing power you steal 20 health per hit and per crit, and with max healing power you will steal 35 or so health per hit.
Also the healing and the damage are completely separate. The damage done also scales with power, and scales a little better than the healing component.
For more specifics you’ll need to ask on the necro forum though as I don’t have those answers off hand.
Thanks. Exactly the information I needed.