In addition to the list above, collecting the supply drop crates in DZ gives I believe 10 PC.
Incursion rewards 10-15 PC for hard (which is kind of an insult)
I don't know about incursion challenge
And just a tiny clarification on the challenge missions - you get 30 PC every time you complete one of them (there's 4 ATM) and you get a bonus 20 if it's the daily challenge (which ends up the same as what's stated above)