1. On the way up - Anything with a good condition gilt dial (5513, 1675,1016) because many of the gilt dials have been replaced over time with service dials. I also agree that the 16660 or the 16600 will be good buys as they might be superseded by another one in the future. Also, anything vintage with a dial that has been out of production for many years. For instance, even a simple airking with an old index dial with original hands. They are cheap buys. Of course, I think the 6265/6263 will always be desirable, along with the milsubs.
On the way down - Not sure. Any Cellini.
2. If I would chose only three rolexes, I would probably go with a simple 5513 (gilt or matt), 6265 and 1675 (gilt with small got hand).