Yes, I believe the Bible is the Word of God...A couple of thoughts on this, though speculating beyond the words in the Bible can be fun, it is probably rather pointless...but here goes! ;-)
1) Snake, yes but...there is a difference...what "spoke" to Eve was not a snake we know as of today, just as the fruit eaten was not an apple. Notice the "Serpent" was subsequently cursed (Genesis 3:14) to move in the dust on the ground; my personal speculative opinion on this is that the curse from God is going to be the most marked impression upon the image of the creature...a sign to everyone looking upon it...I think that whatever it WAS, it used to fly. It may have become the "snake" we now see, which aptly fits the description of the cursed creature.
2) Even today we have people who are "whisperers"; those with an ability to have their spirit be more interactive with the spirits of other creations of the world (horses, dogs, cats, elephants, even plants)...these are people over 6000 years away from perfection; just imagine the communication abilities of perfect humans in a perfect world, and also remember that Adam and Eve were to have in subjection all creatures of the earth. That would not be (and is not) easy without clear communication. Now for some "educated" speculation, when Noah came out of the Ark, he and his family were told they could eat the animals, but also that a fear/dread of man was going to come over the animals (Genesis 9:2, 3); this was something NEW. What if this new subjugation of animals to man involved taking away the main spiritual ability of inter-species communication? This COULD explain both why it was no surprise to Eve that the serpent was "speaking" with her, and she with it, AND why all animals would suddenly be in fear of man. (Remember what happened when Jehovah confused languages with humans? They scattered according to their new "type" which was language.)
