1. The two words aren't even remotely similar, despite both being thrown around like candy.I admit to using the former, no-one is claiming the latter.
2. The game would be piss easy with it, and entire maps would be ruined. Maps like the Miskatonic Library would pose no challenge if you could see everything around you with no risk.
I actually don't know if there's a limited number of lurkers or not, so I just stayed on the stone. However, it made the one shortcut near the beginning impassible as there's no way to get through that much dirt with even the largest steam maximum, so there's something I'm not doing right in that regard (it leads to a gear in the church, but you can get it later).
For the eyes, you can be in its sight and under cover, and bait them every turn. When there are no other party members near, just get behind a wall so it can't see you, and it will disappear at the start of the enemy turn.