JSwartz0181
Chieftain
It doesn't matter if your civ built it first. If another civ builds it, it replaces yours. So if you don't have it, then someone else has it.
As for improving merchants, Great Generals are the +5% gold GP, so the more Generals you have, the more productive they'll be. Likewise, having a market or bank nearby will boost them. And until you get Codes of Law and build a village green, merchants, just like artists and scientists, drop off at the palace, so you want them to be close to that. As such, you'll want to increase the size of your palace if you don't have CoL yet.
As for improving merchants, Great Generals are the +5% gold GP, so the more Generals you have, the more productive they'll be. Likewise, having a market or bank nearby will boost them. And until you get Codes of Law and build a village green, merchants, just like artists and scientists, drop off at the palace, so you want them to be close to that. As such, you'll want to increase the size of your palace if you don't have CoL yet.