Hello,
As was previously stated this is a very touchy subject. As I dont want to influence your decision I will provide you with a couple of things to look up which might aid in your decision making. A good place to start would be wikipedia as it provides easy to understand information and pictures.
Subjects I suggest you look into: Fetal alcohol syndrome (FAS), Fetal Alcohol Effect (FAE), Fetal Alcohol Spectrum Disorders (FASD, please note that FASD does include both FAS and FAE along with a couple other alcohol related disorders, but might not provide the level of insite compaired to looking them up invidiually), Teratogens (then you can follow the links to specific drug effects) and possibly Upper and Lower motor neurone disorders.
All the best.
Regards
Dr Foot
Really I feel this is something you need to discuss in detail with the agency. With such an important decision as this I do not advise you to discuss these children's issues on an internet forum. Just my opinion. You may wish to look up the keywords in search engines and read up on medical websites. Should the adoption go ahead, any responsible agency will both explain the full implications of the conditions of these children and help you and them to assess whether you are suited to each other. I am just a little uncomfortable with discussing these children's conditions, but of course others may feel diferently here. I respect your brave decision to consider adoption and openess to receiving children with complex needs. I hope you get all the information you need and come to the right decisions.