I don’t know if there’s anything in the original Greek that would illumine the first question–both interpretations seem valid, but symbolically, it makes sense for them to look up, since their master is not in a tomb (or the underworld), but has risen.  There is a very poetical aspect to Mark’s language, and poetry is not meant as a literal description of events, real or imagined.  Mark was not a witness to this, nor is it likely he spoke to any witnesses, so whether he’s using some earlier source or just imagining how it would have been, we’re supposed to understand this on a metaphorical level.  Their vision has been raised.

As to the second question, they came to anoint a dead body, and not only is the body gone, but a stranger (who is strongly implied to be a celestial being) tells them Jesus is risen, and they will see him soon.  Wouldn’t you be alarmed, terrified, and amazed?  All at the same time?  I don’t think this needs any explanation.  One thing all the resurrection stories have in common is that none of his followers expect Jesus to rise from the dead.  They all assume he’s gone, forever.  But just going to look for a dead body at dawn is pretty damn scary. 

These are unaccompanied women in a large and often dangerous city, during a tumultuous time of year.  They probably don’t live in Jerusalem, certainly not this part of town, they are part of a cult that the Romans have effectively declared criminal and insurrectionary by crucifying their leader.  It wouldn’t take much to make them run, and I don’t know about  you, but I doubt I’d have even summoned the nerve to go outside, let alone visit a tomb. 

What I ask myself is what might have inspired this story in the first place.  And I actually do think some female followers might have gone looking for his corpse–which I doubt was in a formal tomb, behind a huge rock, but again–poetry.  Allegory.  Metaphor.