I attended a seminar given by a law firm well versed in FDA compliance several years ago and some of the guidance they gave included not soliciting or accepting orders.
In other words FDA draws a line at pre-selling.
You are right about not making claims although I've generally been comfortable for sales and marketing to discuss the general application the product is planned to address and when it might be released for sale (pending FDA clearance or approval, of course).
Also recommended to keep any displays somewhat discreet as at many trade shows, etc. FDA is walking the floor. The more prominent the display, the more likely it would receive negative attendtion from FDA.
There is really very little in the way of guidance in this area to my knowledge.