Adoption, Foster Care or Biological Children?

We are planning to have a 2nd child sometime this or next year. While getting ready for pregnancy, we seem to hear quite a few discussions on adoption and foster care. Even supporting a child through an organisation. Sponsor a child, they call it.

Adoption and fostering is not in our plans for this second one, though when we got married, we did talk about it. It was brought up as an option that if I cannot conceive, then we'll look into adoption and fostering.

One couple whom we know were in the process of of applying to be adoptive parents but have dropped the application due to the difficulty of doing it. Seems like in Australia, fostering is much easier to apply for than adopting.

Has anyone done any adopting or fostering of children? Do you have both biological children and adopted/fostered? Can you share your experiences?