Sounds very weird to have the APU running.
For what purpose?
Pressurization? No...I'm pretty sure the APU is unable to provide bleed air for 1 pack (let alone 2) at cruise altitude, since the APU bleed valve is automaticly shut.
It is simply too weak to provide air conditioning at cruise altitudes.
Might be for electrical reasons, but 1 generator is enough to power the systems, heck you can even fly with the AP engaged with an engine failure.

I havent heard it before, and it's not listed in my books about ETOPS. But I'm not saying it's bogus, you learn something everyday, however I'd be surprised if that was the case.  

I dont have any handy links about ETOPS (try Google) but for a company to receive ETOPS ratings on their aircrafts, their mechanical records are thoroughly scrutinized. Simply put reliability is a heavy factor.
So a new aircraft type or new airline is usually unable to receive ETOPS qualification on the go.

Also, the longest ETOPS range to date is 240 mins, which is a far cry from the original 60mins , to the joy of transpacific airlines  

Little advice from me to you.
If you want true facts and accurate information, don't read airliners.net forums.
So much of the posts over there are garbage and nonsense.
There are way better forums than that, PPruNE for example.