The joint smoking mohican geologist whose responsibility was to map the entire structure with his pups but managed to get lost in the temple is called Fifield.
The biologist who was frightened by the sight of the beheaded Engineer but wanted to hug a hissing strange looking snake is called Milburn.
I do know their names...
For your first point:
1) He smoked marijuana while stressed out and stuck in a deserted facility. He wasn't working, he was anxiously awaiting the end of a storm and the rising of the sun.
2) If my memory serves, the map is on the Prometheus, not with him. I do not recall if he has access to the map, but I don't think so. I know he has coordinates, but those are about as useful in an unknown location as finding your way through a forest with longitude and latitude. How they got lost is beyond me. They did blindly follow a hologram, so that probably played a factor. Why they weren't in contact with Janek to help is also a mystery. Maybe he thought 'they got this''. Maybe he was busy with tracking the storm progress and looking at what the main group was seeing. Maybe they didn't know they were lost until it was too late, and thought they were going the right way and didn't ask for help. Or, maybe it was simple plot convenience.
As for Milburn:
1) So what, he was creeped out by a beheaded giant bipedal alien.
2) He didn't hug it, he reached out to pet it. It had a very small mouth, logically not small enough to contain fangs, like other snakes its size. Indicating it would either have small teeth, or be a constrictor. At that size, it wouldn't be a very strong constrictor. However, back to what was on film. He was confident that the gloves and suit would protect him. Like how people tease lions through the glass at zoos. Except there was no possible way he could have guessed it would be bone crushing strong, bleed acid, and regrow limbs instantly.