Each hunting region has its own monster types and level ranges. Check a target’s level before attacking, and move to tougher areas as your character grows. Monsters chase nearby targets, return toward their spawn area and respawn after death.
A kill can drop gear, and gear rolls its own quality and sockets as it falls — most drops are Normal with no socket, and a Super drop with two sockets is rare enough to be worth the walk back. Kills also drop potions and arrows, and much more rarely the upgrade materials: plus stones, quality stones, Meteors and DragonBalls.
Loot belongs to whoever earned it for a short while before anyone may take it, and it disappears if nobody does.