In typical governmental fashion the 9% penalty is spelled out and exact but the "bonus" can't be calculated until they know how much in penalties have been paid and then it is a linear depending on how many people qualify for the bonus.
That is mostly due to the program being budget neutral. As a taxpayer, I don't mind this so much. It does make it a bit harder to see what the bonus will actually be. Max bonus I have seen so far is + 1.87%.
One thing to keep in mind, the penalties, much like the bonus, work on a sliding scale. Unlike MU where if you missed one thing you failed for the whole program, MIPS works a little differently. Say the target to avoid a penalty is 70 points, and you got 60 points. You do not automatically get the 9% penalty (which is the max). You could get only a 1% penalty. So in that case, even if you are not "passing" it is still worth submitting what you did do to lessen the penalty as much as possible.
As for PopHealth. Its a new interface, and it is actually the first of its kind (with any EHR) to connect directly to CMS. We are able to pull your actual MIPS score year round from CMS, and we submit directly to them at the end of the year (no more downloading or printing a bunch of different files and manually punching in the numbers on the CMS site). Plus, as I said previously, the workflows for the measures are pretty easy. Just send me an email and I can set up a time to show you.