If you know;

1. Frontal area
2. Aerodynamic drag factor

How do you "know" these two?
How do you determine when they are changing
due to a change of your position?

3. Grade
4. Barometric pressure
5. Grade

Are 3 and 5 different?

Maybe 5 should be "wind"? (direction/strength?)
That's what the "PowerPod" measures, right?

You could calculate the amount of power you are applying to drive the bike forward. This would be a little off

"a little"? that depends on how well you "know" all those input
parameters.
Moreover, "rolling resistance" could be a bigger factor than
"Barometric pressure" (time trial tyres vs "studded" tyres?)


--
Note: please read the netiquette before posting. I will almost never
reply to top-postings which include a full copy of the previous
article(s) at the end because it's annoying, shows that the poster
is too lazy to trim his article, and it's wasting the time of all readers.