Not sure if anyone will find this useful, but just thought I'd catalogue all of the missions, their energy costs, and their rewards. Especially interesting to me are the ratios of xp and gold rewarded to energy spent. Took me a while just to add Kain's Crest, so I'll just start with that and add more in the next couple of days. Please let me know if any of the info needs to be corrected.

Kain's Crest

Feed on Humans
5 energy, 3 xp, 40 gold, 0.6 xp/energy, 8.0 gold/energy, 0.6% legendary, 14.2% rare, 20.2% common
Search Kain's Crest
5 energy, 3 xp, 40 gold, 0.6 xp/energy, 8.0 gold/energy, 0.6% legendary, 14.2% rare, 20.2% common
The Rotting Baron (dungeon)
3 energy, 10 xp, 25 gold, 3.3 xp/energy, 8.3 gold/energy, 2.3% legendary, 22.6% rare, 75.2% common
Track Stolen Ambulance
4 energy, 1m, 3 xp, 45 gold, 0.8 xp/energy, 11.3 gold/energy, 0.6% legendary, 14.2% rare, 20.2% common
Glamour Frans LeCroix
5 energy, 4 xp, 40 gold, 0.8 xp/energy, 8.0 gold/energy, 0.6% legendary, 14.2% rare, 20.2% common
Follow the Horde
3 energy, 2m, 3 xp, 45 gold, 1.0 xp/energy, 15.0 gold/energy, 1% legendary, 22.3% rare, 31.8% common
Zombie Street (dungeon)
3 energy, 10 xp, 25 gold, 3.3 xp/energy, 8.3 gold/energy, 2.3% legendary, 22.6% rare, 75.2% common
Glamour Thomas Berg III
3 energy, 3m, 3 xp, 50 gold, 1.0 xp/energy, 16.7 gold/energy, 1% legendary, 22.3% rare, 31.8% common
Investigate Ghoul Attack
3 energy, 3m, 3 xp, 50 gold, 1.0 xp/energy, 16.7 gold/energy, 1% legendary, 22.3% rare, 31.8% common
Track Down Ghouls
3 energy, 2m, 3 xp, 45 gold, 1.0 xp/energy, 15.0 gold/energy, 1% legendary, 22.3% rare, 31.8% common
Home Invasion (dungeon)
3 energy, 10 xp, 25 gold, 3.3 xp/energy, 8.3 gold/energy, 2.3% legendary, 22.6% rare, 75.2% common
Glamour Det. Harris
3 energy, 3m, 3 xp, 50 gold, 1.0 xp/energy, 16.7 gold/energy, 1% legendary, 22.3% rare, 31.8% common
Break in to Blood Bank
4 energy, 1m, 3 xp, 45 gold, 0.8 xp/energy, 11.3 gold/energy, 0.6% legendary, 14.2% rare, 20.2% common
Apply For Kill Permission
3 energy, 5m, 5 xp, 50 gold, 1.7 xp/energy, 16.7 gold/energy, 1% legendary, 22.3% rare, 31.8% common
Ghouls and Goblins (dungeon)
3 energy, 10 xp, 25 gold, 3.3 xp/energy, 8.3 gold/energy, 2.3% legendary, 22.6% rare, 75.2% common