1 - I tend to think of 'inbound' as used with moving objects, such as trains or traffic. 2 - See comment in #1. 3 - What you have is best. 4 - to take a phone cal = to answer (you may receive one that you don't take)
In addition to Philip's answer, I would say that often, inbound means that something is heading towards "in", whereas incoming implies actually in the process of arriving. The distinction is not clear though.
(1). In the case of phone calls, incoming and inbound have the same meaning, although again inbound may not have the immediate, "happening now" nat