The Fun Pimps

You should be able to hit any zombie you see regardless of whether they are dormant or not. Must have been a glitch or you were using your trusty primitive bow which has the super power of sliding between and through hitboxes....

You can go into POIs any manner you wish but you will get some weird spawns and often see things spawn in right in front of you if you aren't sticking to the prepared pathway. But the POIs are voxel so feel free to chop through however you want. You should still be able to hit any NPCs though.