Is there an easy way to turn NPCs and monsters into statues? I want to use some in a house I'm making. They don't have to be stone textured, just stay in place in a specific pose.

DisableAI is what you're looking for.
It would be almost impossible to get them to strike a particular pose consistently however.

You could in Oblivion. They made quite a few NPC statues in that.

THIS IS SKYRIM!!! *kicks Pendragon into pit*

Or...

Skyrim and Oblivion do not share all of the same features.

if you want a guaranteed posed statue, take a look at the LoadScreen actors in a 3d editor and copy how they did them.

i made a few character based load screens, and since they are STAT objects and not actors, they can be physically placed into the world and will remain motionless forever with no scripting involved. they dont have any collision though, so you should use a collision box around them.