QF Internation online check in and pre assigned seats

[p-dub]

Hi all,
On my upcoming flight back to SFO this Wednesday, Qantas has pre-assigned me (and girlfriend) seats 35 A & B.
A few questions:

Are these set in stone?

Should I use the online check in facility now available to ensure we get these seats? And if I do, does this limit my slim chances on getting bumped upto Business Class?

Thanks in advance,
Patrick.

[tuapekastar]

Never set in stone p-dub, but I've never had them changed on me either (other than for an a/c sub).

If they're the seats allocated to you then it's likely they're what you're going to get.