An older thread covers this, and has an authoritative reply. Unfortunately, dzablocki is incorrect.
1. Does exchanging opium for another good in the market move the marker on the opium track?No, it doesn't move. You can think of the market's ability as an upgraded version of the "2-for-1" action (which also doesn't move the opium marker)
2. Does exchanging opium for 2 goods in the opium den move the marker on the opium track?Yes, it does move