Remember that intelligent life is very adaptable, and that alone allows intelligent life to fit into a variety of niches. At this point, you're getting into some very fine details, so ask yourself not what you need to know, but what you might need to know just in case. You may have to deal with questions of evolution, genetic engineering, etc. Its worth taking some time to learn a bit about these subjects, as people have many assumptions that aren't correct. As you may guess, I consider culture a vital part of intelligent life.
Culture is what intelligent life creates and passes on - rules, ideas, language, ways of thought.
Genes may be complicated, but they're passed on usually through limited ways. Culture can be acquired over time, improved, and even devise ways to pass itself on - language, publishing, etc. Humanity is seen everywhere on the planet, under any condition, in every environment - able to adapt and pass on ways to survive. The elements of a culture exist for a reason - at least at first. What controls does the culture have to keep things within it from malfunctioning.