I think this is something that we should start to address now. If life-expectancy continues to rise with improvements in modern medicines, etc. then starting now will help to preserve our future. From a less...charitable standpoint, I feel that if you're not capable of financially supporting yourself, you shouldn't be able to have a child that you will not be able to support. 13% Percent of children are born poor, and of these an estimated 49% will remain poor for at least half of their lifetimes. While there are success stories, this creates more problems than it is worth.
Some developed countries have a declining population, particularly when you account for the impact of immigration. This has been achieved through improved healthcare (knowing that your children will survive/access to contraception), improved education (sexual eduction/access to better jobs), free commerce and media (increased importance of lifestyle and material possessions), equal rights (women in control of their own future). Therefore, I think the focus should be on sustainable development. On your second point, I don't understand why those from more affluent backgrounds, with access to a better education and opportunities, should ultimately be provided rights that are not afforded to other less fortunate people.
Birth control is huge. Widespread access and a focus on birth control/contraceptives as opposed to abstinence in public education could do wonders in the long run.