I have a sneaking suspicion that the answer to both questions is "No", although I can't be absolutely sure.
First, as far as I know, a 3.2MP camera just doesn't have a high enough pixel density to record a 720p image, even as a still image. And most phone cameras record even lower res images when in video mode. Of course, I could be wrong. Or, a hack to do so might be discovered, so feel free to hold out hope.

Though, if I recall, the Nexus One had what, a 5MP camera? The difference between enabling hidden modes of operation vs. actually physically increasing the level of detail the camera picks up is a big difference.
Second, as far as T-Mo's Optimus T having a better audio codec.. Do you mean voice phone call wise? I'm guessing you do. If that's the case, I'm also almost sure that we can't get it, due to technical differences between the way that the CDMA (what Sprint uses, and Verizon) and GSM (T-Mo & AT&T) phone systems break down/organize the transmission of voice data. It's been a long time since I dug into that, but last I recall, the protocols are different, and incompatible. Sorry.
Having said that - I commend you for wanting your phone to be capable of more than it currently is. It's when people think like that that we are led to find out just how far we can push the hardware.
I remember before Nexus S came out with the actual 720p recording update, people were able to modify something to allow the phone to do that.
Would it be possible for the Optimus S' hardwares to handle 720p recording? Also, I heard that the T-mobile version has a better audio codec in it, can we somehow get that on ours too?
Thanks!