well i cant answer for cole's reasons for going behind arsenal's back. however, im sure his thinking is that if he has a meeting in private, first. once he can see that the offer on the table is "doable", then he can tell his bosses at arsenal that he wishes to leave and that chelsea have offerred him a good deal and he wishes to act upon it.
now, if he puts in a transfer request before meeting chelsea, arsenal accept, he then speaks to mourinho/chelsea and they give him a bad deal (eg. if u move here ashley, you will be on the bench most of the time), then cole is well and truely screwed. its difficult then to tell his arsenal boss that, "erm, gov, i know i wanted to goto chelsea, but they offerred me a bad deal, so i wanna stay now". arsenal will probably tell him to get lost. to avoid this situation, he first wanted to see what chelsea were all about before he made things official.
u c, in most cases, tapping is unreported, however, in a few cases, you do get found out and whole hell breaks loose, which is what has happened to cole. by leaking the story, mouriho has increased the chances of signing a player that he has his eye on. he is very cunning.
on the subject of "does cole owe anything arsenal?". if u were employed by a company for 10 yrs and during your tenure you became the best at what you do, are you trying to tell me that for the rest of your life you are stuck with that company, no matter what the terms of your contract are? as an employee of the club/company, do u have no right whatsoever to leave the club/company for a better deal? i fail to understand why he "owes" arsenal - please explain.