Question: In trying to set reasonable limits on a PC's usage of the polymorph chain of spells. Is it plausible to require that the PC have some form of interaction with the target creature? Or can a PC polymorph into a creature that the PC has only heard about? Or read about in a book? Or seen just a painting of? From a solid role-playing standpoint, it seems reasonable to require that a) the creature exists in the multi-verse that the DM is running, and B) the PC has some knowledge of the creature. What is the minimum "knowledge" that the PC must have in order to polymorph into such creature?

Answer: 
Yes, it is plausible to restrict polymorph to creatures that the players have encountered. This is one of the commonly discussed polymorph house-rule.

I think the minimum knowledge would be determined by a [knowledge skill](http://www.dandwiki.com/wiki/SRD%3aKnowledge_Skill) check for that monster. If the monster does not exist in your multi-verse this check would be impossible to complete. Basic knowledge of a monster starts at 10+HD, but I would extend this to be 10+HD+X, where X is creature dependent (maybe based on the number of special abilities the creature has).
I recommend handling polymorph spells the following way: The player casts polymorph, wildshape, etc and tells the table what he's turning into. If anyone at the table then exclaims any of the following phrases: 'What?!', 'The hell book is that from?', '', 'That's (ridiculous/stupid/a travesty)', 'Quit being a douche', or 'Nuh-uh', then the casting fails and he gets to try again next round.

The best solution for all player problems isn't codifying a rule base to eliminate abuse, it's making it immediately clear that Player X's shenanigans are making the other people at the table have less fun.