the life leech in crystal caverns
 

Can any stag terror be a PH for life leech eveven the ones near broken bridge? or only ones near the spider caverns?

Not confirmed but I believe from my experience that the named Terrors only spawn in their hallway area and cavern marked six on the map.

I agree with above, only in the cave and the hallway. not including the 4 on the dais above the bridge

can spawn in hallway before geonids11

Anywhere
 

I had one spawn at entrance to the tunnel, killed one in the middle and ones it poped near entrance to the end cave. So, I guess it is a random spawn.