I've never heard of needing 3 coats of opti-coat.. Sounds like he's making up for the loss of business of you showing up every few months for a polish and wax
As far as the clear coat comments, I believe it's the best way to describe it vs. a wax or sealant to differentiate it to the average shmuck (rightly or wrongly). It apparently (I'm no chemist) bonds more tightly. This (again apparently) results in a *virtually* permanent layer. Yes, the word "permanent" is loaded, but the longest test I've seen has been 3 years - coupled with the fact that the only way to remove it is to compound it off.