SS/PS Passing through the guarding spells

[ginny343]

No: HPFGUIDX 129433

I have some questions, but I am quite sure they must have already 
been discussed.  I'm hoping someone can help me with some ideas or 
links.

Okay, in SS/PS when HRH go through the trap door and face all the 
tests, the only ones that show signs of already being passed are 
Fluffy (sleeping/harp) and the flying keys (crumpled feathers).  I 
don't see the Devil's Snare being too much of a problem, if you get 
up right away.  But what about the chessboard?  Did Quirrel have to 
play his way across it too? And then did it clean itself up to be 
ready for HRH?  
And then how about the potions.  The one Harry finally drank from 
was so small only one person could drink from it.  I don't think is 
looked as if someone else had already taken a drink because then it 
would have been obvious which one was the right one.  So, how was 
Quirrel able to pass?  I think the stone was being hidden from 
everyone, not just students, so I would assume older wizards 
wouldn't be able to just walk through some of the tests without 
having to do them.  

Sorry if these are very old, boring questions.  

Linda