Please read your questions, they are not coming across very well. The question in your first post does not seem to be at all related to what you say you are doing in your last post.
How to tell what wire is which on older home wall lightswitch
In your last post you ask,
I'm also asking if I have enough wires at both boxes to complete this circuit.
How should we know, we aren't there and we don't know how many wires you have. Note that you said "circuit", implying a single circuit.
You said you were running one "feed circuit" to the top of the stairs for the fan and one "feed circuit" to the bottom of the stairs for the light. That implies two circuits. Does that mean you want the fan and the light to be on different circuits? You also said that this was your last circuit, again implying you are running only one circuit. Quit confusing.
Neither the light or the fan pull very much power so the combine load does not justify two separate circuits. However, I recognize that there may be other reasons you may want them of different circuits.
If you want two separate circuits you can run a circuit to the top box for the fan, and a circuit to the bottom box for the light as you stated. Or you can run two circuits to the top box.
If you mean you want run one circuit and feed the top box for the fan and feed the bottom box for the light, that is not necessary. You can feed both from the top box.
You will need 3-wire cable between the two boxes no mater what you want.
Just tell us what you want and we can tell you how to do it.