In response to your first request, I just created a Icon Library field that should be out in a day or two after I finish debugging it.
What do you mean by a Setting’s API? Can you elaborate a bit more on this? I’m interested in seeing what you mean by that.
As for the other fields, you could create your own field or extend some of the fields already created, have you taken a look at creating your own field type in the documentation? http://www.advancedcustomfields.com/resources/tutorials/creating-a-new-field-type/
