Based on anecdotal evidence and several trial runs, it is the theory of many players that NPC towns have all technologies at the towns level (lvl 3 city, lvl 3 technologies / lvl 8 city, lvl 8 technologies). In addition, it would appear that there is nothing to be said about prerequisites. So lvl 4 cities have lvl 4 Privateering, etc. The only thing that throws a monkey wrench into the theory is troop type.