Don't give up and good luck. PPC dating isn't going to be easy but if you can make it work everything else will just be a lot easier.
You'll never hit a good enough CTR to get your bids down targeting as broadly as you are. And you will never be profitable on a $4 dating install when you're paying $0.75 a click because your CTR is so low. You need to rethink how you're targeting users.
1) Yes. You need to split test ages. Or any other thing you can think of. Target race. Target geographically. Interests.
2) Typically Ads burn out quickly on facebook. Basically you'll see a pretty consistent drop in CTR until it becomes unprofitable. Also depending on the time of day. The day of the week. The time of year. Your CTR will be dependent upon all of this.
Don't give up. Man up.