The ones that say 0 perfumes are required, still need at least 1 perfume to open the window but the perfume won't be consumed.
The rare level is the weapon/armor rare level, not the shell.
This is a pic i found, the original is from imageshack so dunno who is the owner. Also there is a thread on nostale.uk forums about this but since this forum is smaller, i guess it would be easier for you guys to find it here.
Edit: pic fixed
Last edited by ken030980 on Sat Jun 02, 2012 8:46 am; edited 1 time in total