Managing Large Empire

I recently invaded a empire that had 12 countries. However now that I have acquired them I now have 19 countries. I was wondering how you can manage a lot of countries, if it is better to transfer the population of all my new 12 countries to perhaps 3 of the countries I conquered and get rid of 9 of the countries I conquered perhaps. Additionally I was wondering how you can fix high average age I was wondering If I got rid of all my hospitals temporarily to let the age go down? Also I was wondering if by transferring my population if that could affect average age? I do not mean transferring workers but population.

The larger your empire, the higher your govt costs will be. I think 9 is an optimal maximum number of countries to have in your empire. Would transfer but take caution with your population demographics after that. I think the transfers will cause your avg age to rise your population will begin to die off.

In the beginners section of the forum Zen has created a guide for transferring population without the death syndrome that follows.