I am really glad you started using TeamPulse.
For more information on relationship types usage I may suggest you this part of the TeamPulse online help:
Also if I understand correctly you need an easier way to change the relationship types, mostly between stories? So if you have selected "affected by" but afterwards decide that "child" one is better, you want to switch easier by just selecting the other type of relationship?
And to answer your last question - here is an example of how we are using this functionality for stories relationship. When we have one let's call it "epic story" which has few more sub-stories, then we create parent -> child relationship between these stories. The epic one is parent to all other sub-stories. Also note that when some story is marked as parent to another, then when opened the second story it is automatically set as "child" of the first one.
Hope that the information above is helpful for you and if you need more details, please do not hesitate to contact us again.
the Telerik team