Regardless of what the Catholic Church teaches, ever person retains the freedom to do whatever they want. If you really want to use birth control or have an abortion, the Church can't (and wouldn't) stop you.
However, it is the Church's role to instruct on moral issues, and the Church is perfectly free and right to make statements about the morality of using birth control, seeking abortions or performing abortion. One assumes that somebody who has chosen to be/become/remain Catholic would pay heed to what the Church instructs on these issues and strive to meet the standards set. For others who are not Catholic, one assumes that they may or may not pay any attention, according to their own personal beliefs.
Furthermore, I think it's important to note that the Church 'puts its money where its mouth is' on these issues. Classes giving instruction for the new, scientifically proven systems of natural family planning are provided through the Church to help couples plan their families responsibly. And no other religious organization has more programs to help women in crisis pregnancies with food, clothing, shelter, moral support, and other forms of assistance.
As for the "AIDS in Africa" argument, the Church is being logical and factual in stating that abstinence before marriage and absolute faithfulness afterwards is the only real way to avoid AIDS. Even the World Health Organization, a pro-condom organization, admits that there is a 90% failure rate in using condoms to prevent HIV transmission. Do the math. If 100 people in Africa use condoms when they have sex with HIV+ people this very night, you can only count on 90 of them not being infected. And if those 90 rely on condoms next week when they have sex with HIV+ people, you can only count on 81 of them coming through it unscathed. You know how to add and subtract, so I'll let you figure out how long it will take for half of them to get HIV. Condoms have been distributed by WHO and Doctors without Boards and many other organizations for the last 20 years, and there's still an AIDS epidemic. It just doesn't work very well with a 10% failure rate, and I for one think the people in Africa (and elsewhere) are important enough that we find another solution. So far, the only proven solution is abstinence before marriage and total faithfulness afterwards, so there's nothing wrong with recommending it. People will ignore that, of course, and they're free to take their own lives (and their partners' lives) into their own hands if they want to, but there's nothing wrong with the Catholic Church promoting the ONLY solution that is proven to work.