How long have Bonobos as a speces existed, and is it believed they have always been as promiscuous as they are today? What is the average life span of a bonobo and what is their infant mortality rate? What is the main cause of death of infant bonobos and of adult bonobos? Do sexually transmitted diseases exist in bonobos? If so, are they life threatening or cause reproductive problems?
In human society, those who live as promiscuous as bonobos tend to have short lives due to disease if not medically treated, and can also lose the ability to produce healthy offspring. How have bonobos managed to survive as a species living the way they do? How close are we humans to bonobos genetically? Is it possible that bonobos hold the cure to certain disease's in humans? Are there any primatologists currently studying these issues?

Dear Mitchell,
                        Chimpanzees and bonobos diverged around 1.5-2 million years ago, based on genetic studies (Perry 2007). The fossil record if these groups is not very good.

As they occupy a different niche from chimps many of their character traits have possibly been with them from speciation and bonobos have different group dynamics and use sexual contact as part of their group cohesion mechanism. Promiscuous is a bit of a loaded term, as it has moral overtones that probably don't apply in bonobo society. 

This site has a good information file that answers most of your questions about lifespan and general information for the species

Apes (including H. sapiens) have to deal with STDs and bonobos are no exception. I can't find much information about the effects but Julie Rushmore seems to be the person who may know … arship-38/

As an aside, STDs, like all diseases, have an evolutionary history and can vary in their impact on their host. Many STDs that are now feared by humans did not come into being until population densities increased. The morbidity of many diseases also decreases over time, so the notion that having a STD automatically reduces fitness and leads the carrier to die younger (which may or may not affect their lifetime reproductive success) does not follow. You could have many offspring, die young, but still have a greater representation of your genes in the next generation (which is the measure of fitness). The worst outbreaks of STDs and other diseases often involve carriers who display no symptoms. 

I can't find anything about investigating bonobos for STD research for human health purposes and given the lack of information about which diseases affect them, it would be hard to justify.

"Hope is a duty from which palaeontologists are exempt."
David Quammen