The factors like age, education, etc., impact your disability "multiplier" (that range from 1-6x the medical impairment rating), in a pretty logical way, once you think about it.
The more education you have, the lower the multiplier would be; the older you are, the higher it would be; more medical restrictions, higher, etc. Just think about how all of those things impact someone's ability to work and/or find work. It's not a precise mathematically formula that says if you have a certain amount of any one factor, you get a set multiplier. It's all taken into account in a big picture kind of way. With settlements, you just lump it all together and decide where it should fall from a logical standpoint.
A college education hurts you in the PPD area, because it's a higher level of education. Age over 50 and medical restrictions would help increase that, though. If she's not returned to work because of the injury, but has a college education, then I'd suspect you're likely somewhere in that middle range of about 2.5x-3.5x the rating. Again, that's just a ballpark, and it's also subject to some negotiation.
As far as the reduction you're talking about, past TTD payments really wouldn't have anything to do with that. I was mentioning that there's no specific reduction for paying benefits in a lump sum. The employer/insurer would get a credit for any advance payment of PPD benefits after the MMI date against any final settlement amount. The workers' compensation statute basically says that if a person can't go back to work after MMI, that the TTD benefits still stop, but if there's an impairment rating, the insurer should still pay up to 60 days of benefits, which would be credited against any PPD that would be owed. Basically, she'd be getting a small part of her settlement early, before it was approved.
I hope this helps.