You set stat growths in the Actors Tab (in XP. In 2k3, it is the hero tab) of the database.
For stealing HP/MP, you can do that with variables, though that can get complicated (depending on how much depth you want the skill to have. It's actually not too too hard). In XP, you can also do it with scripts. I believe there are a few already out there. Maybe trickster made some ... I'm not sure, but they're out there.