Nick
What you see is a real possibility..i would really need to get out there and see what else is around. But it is too darn hot!
The window..i am not sure what it is. More signs, uncovered hole or a window. I've not examined it nor actually tired to follow signs/symbols in this local little area. You must remember..i am not expert at all so it is mostly speculation on my part.
I started out simply trying to follow/recognize trail markers. And that is what i am still doing almost a year later lol. Which works out well for me. I can only comment on what i think...not that it is truth. I've not looked closely, climbed all over this little spot.
The little vignette of seated guy has a lot of "advanced" signs and symbols (read that to mean i do not know positively what they mean..

) But i never actually took a bearing from his sharped face...so you could well be right. Two faced ...well thats a janus.The detail carving of his sleeve his interesting. The placement of his hand is interesting. There is a lot quite interesting about it and i am rambling.
The other little pointers would need better pictures.
Out of place rocks are good thing to notice as you did. Likely significant.
Over all your take on the matter looks reasonable to me..and i thank you!
I sometimes take a compass reading from one marker to another to check for patterns of alignment. Can be surprising.
Well..td..seated guy must have been hauling a heavy load ..cause he has been resting for a few hundred years..lol.