So can I confirm before I solder this up. What all was said here wasn't immediately apparent to me till I drew it out quick, and I think it would help others like me that aren't quite as circuit savvy as a lot of you.
So a low pass filter configuration like this:Yup - I agree with this, resistor should be added, hence the name RC filter;) For simplicity I left it out, but to be correct it should be there.

I also wanted to confirm that the 10K resistor in that last drawing is not ideal if we are dropping a 0.47uf cap in there. 680 ohms was stated earlier in the post and it looks correct for the RC filter?
C = 0.47uf
f = 490 - 500Hz
R1 = 677 - 691 ohms
EDIT
I removed the rest of my post as it had PWM calculation results that were wrong and confusing to the point of wiring this circuit