in reply to order of hash
See the above replies for more understanding of the technical issues than I can give, however I would point out that the practical upshot of all of this is the guarantee provided: Writing code which relies on the assumption that this order stays constant may work in your particular implementation of Perl, however this is a bad idea on the basis that it may break with a future revision of the language: There is no guarantee that this behaviour will not change.
Please, if this node offends you, re-read it. Think for a bit. I am almost certainly not trying to offend you. Remember - Please never take anything I do or say seriously.