Ex cop I used to work at had one woman blow a .32 and she was still able to walk. Took her to the hospital to confirm it, they got .30 by the time they got around to her, then wouldn't let her out of the ER until she'd dropped below .16.
While amazing that she could still walk, I'm willing to bet that she was hella impaired.
And yeah, results higher than .24 is certainly possible, as "how aren't you dead?" levels come up regularly.
I wouldn't object to raising the level back to .1, and while I think I'd prefer .05 more than .02 per step, that's more a matter of optimization than a real difference.
And yes, you need to actually enforce driving on a revoked license.