Please explain how it raises money with a tax rate that's below the existing corporate tax rate
It's a similar concept to Alternative Minimum Taxes [*], which you probably haven't experienced with your own taxes. Basically, deductions that corporations can normally claim are disallowed and then their taxes are calculated at the lower rate. If the result is more than they would pay with the higher rate and broader set of deductions, then they have to pay it rather rather than the normally-calculated amount. So it doesn't apply to all corporations, or maybe even most, but it extracts additional revenue from those that would otherwise be successful at using extensive deductions and credits (also known as "loopholes") to reduce their tax liability.
and based on behavior specific behavior that corporations aren't necessarily going to engage in
In some cases they're already committed to the behavior and won't be able to avoid the tax. But, yeah, in many cases this tax may deter the behavior rather than raise revenue. The CBO's projections try to take that into account when projecting the revenue impacts, of course. But I think the main goal of this part of the IRA is to appease populists on both sides who think stock buybacks are bad, because they don't understand how publicly-traded corporations work.
Meanwhile we're spending money now that will only be hypothetically raised in the future?
The grants will also be paid out over time, so it's more like spending money in the future that will be raised in the future.
I don't believe that will help to reduce inflation in the slightest.
Yeah, it's probably inflation-neutral. The IRA does contain some inflation-reducing provisions in specific areas, notably healthcare, but it's mostly revenue-neutral and inflation-neutral. I suppose you can say it's inflation-reducing compared to its previous incarnation, the Build Back Better bill, which if enacted would have increased the deficit and potentially stoked inflation.
[*] Note that AMT is slightly different in that for most taxpayers AMT is actually calculated at a higher tax rate, in addition to disallowing a lot of deductions. But AMT also allows a much larger standard deduction (with a phaseout based on income).