Another Rookie Q? Two buildings in a province (Amazons/Griffin)

[Hector, tamer of horses]

Experts

As I am new I really don't understand how all of this works.

I just conquered a province that had Amazons and Griffins on the build list. The resources available were small and a temple was required to build the Griffins.

So I built a Temple and could build a single Griffin and a single Amazon with the available resources. I wanted to see how good these troops were en masse, so I built a fort to try and jam up the resource count. Well that worked well enough, but in the process my temple was deleted when the fort was built(hence no more Griffins).

1) Is that supposed to happen? Is only one structure per province allowed (my capital has many) or did I break some rule?

2) My first combat with Amazons and Griffins resulted my sustaining very high casualties. I am wondering if I am using them right. My massed TC bowmen, fronted by heavy infantry, seem to do far more damage to my enemies without nearly the damage to my own guys. Am I using the Amazons and Griffins wrong? What is the correct way to use them? Are they a waste of money and effort? Do they have any advantages?

Thanks