What is the ruling on and limits of female friends discussing very private and very sensitive topics, including describing their bodies or men's bodies, and using offensive terms?

There are no specific limits to conversation between female friends, except for the boundaries of what is permissible and forbidden in Islamic law. There is no harm in discussing physical attributes as long as it does not devolve into indecency or lead to corruption and temptation. Similarly, mentioning the attributes of men is permissible as long as it does not entice indecency and lead to a prohibited act.