The current rewards are fine, it's just the tasks that need changing. One task should not require you to run all over the world when it's just a repeatable.
Make sure each tasks requirement are close to each other, i.e you could have a Amazon and Valkyrie task for earlier levels, Mummies and Vampires, monsters that tend to be close to one another.
Sure you can make chains that are onetime tasks like the "Gather Supplies" tasks, which can give exp, rare items and generally anything based on how long and hard the tasks are.
On another note, I feel that the exp stages might be a bit too high in the start.
Have you tried so you don't get too high in rook, cause last time just doing the dwarf quest pretty much got you to 8.