U nfortunately I doin't think there is any standard way to approach them. I would go in and be frank about it really. Like you have stated, I have a replica watch, that has 7750 (asian), would you be prepared to service it.
Again no standard answer to this one. If you go through our trusted dealers, you will receive the watch. As far as which Navi to go for, I can't really help there. I have a two tone Navitimer that has dials at 12,9,6 on a strap and love it. Another member, and also a big Breitling fan has one at 3,6,9 and it looks awesome on the strap too.