having population will increase
1. tax income
2. labour
3. plunder income
4. reward cost
5. base power rating
6. Consumer Goods Demand
Having Population will decrease
1.food income ( unless gaurdian who dont consume food )
2. Apeal To the Enemy ( having a high base pr when nobody knows it will make it look like you actually have a powerfull fleet , this will scare off lesser empires )
3. Defence/offence ( having a high base power gives you less defence than those who dont , this can easily be removed by climbing higher in PR to a point that your base pr makes little difference in defence/offence )
4. Consumer goods production