After settling a city, and after it grows enough to specialize as a fortress, town, or conclave, should I limit the building to things that are along certain lines? As I develop, it's tempting to build everything because why not increase growth? More gildar is better than less, so let's get a merchant too! Same with production, etc., but at some point shouldn't I stop and set the city to produce wealth or research and leave it alone? How much building is enough?
City Improvements in FELH have no maintenance costs so you can build as many as you want. The end result is you're always better off w/ more improvements, but there's a balancing act, especially in the first 150 seasons, between building improvements and training troops / pioneers to secure / expand your zone of control.
While there is no mandatory blueprint you should follow, I tend to think the most important improvements for any cities are +production improvements (e.g. Workshop) and -unrest improvements (e.g. Bell Tower). Once you have unrest in check and a decent production, then building orders are fairly dynamic, depending on what the situation calls for.
Also, keep in mind "wonders" (e.g. Merchantcross Bazaar) can only be queued in one city (worldwide); there's no race to see who finishes first as is the case in, say, Civilization; the race is about who puts it in their queue first (and then that wonder can only be built by that faction).