I'm about 90% sure the ST60 has audio out but I have no hands on experience with them, so I'm just going off the internet here.
(anyone feel free to correct me)
I was kind of suprised that my Samsung Plasma didn't have analog audio out (not even a headphone jack) but I wouldn't be using them anyways.
As for HDMI and receivers, if you don't feel like you must have things like bitsreaming HD audio etc then it's up to you to make the switch or not, the greatest convenience in my mind is just that, convenience it makes everything that much easier to setup and use when I can hook everything up through my AVR rather than having to change channels on both units I just do that on the AVR itself, and my signals have to go through the cable box anyways..
As for audio desynch, that's really not something I can really comment, again it probably shouldn't be an issue but it can be, I would personally just wait for the tv to arrive and see if you can hook it up as you want, it should work without issue, it does here, but then again I'm on the other side of the planet.