The heartseeker is a wonderful weapon and is nearly as good as the Short bow of Gesen. Wisdom is all that could be higher. The rogue should be a common thief and should specialize in two-handed weapon style and short bows. Intelligence doesn't need to be any higher. The priest should be a common cleric and specialize in two-weapon style, flail, and war hammer.
Intelligence is, amazingly, nearly worthless for a priest.
The warrior should be a Kenai and should be dueled at level 9. The newly dueled wizard should be a necromancer and specialized in two-weapon style, katana, and long sword. Wisdom shouldn't be increased anymore than it is. All of this has been researched for a LONG time and all of this information is totally true. This design is the most powerful setup for a party.