I wanna buy a Usa made standard stratocaster made in 2008 online.
What is going on with (most of) the tuning stability on this one when using the trem?
and i was thinking about buying it in olympic pearl what is the truth about the aging yellow?
Thanks

Cant speak about the "aging yellow" , but had one and NEVER had a problem with tuning using the trem. I have never heard anyone complain about that issue.They are great guitars.Once they are setup ,there shouldnt be any issues with tuning at all.

Most people tend to agree the 2 point trem system is more accurate with keeping in tune (trem stability). There will still be people who think otherwise. For 2008 models onwards they have vintage steel saddles instead of the block saddles.

The American Standard in pearl white is polyurethane.
If exposed to light it may change color eventually but it takes a long long time.
Its not going yellow any time soon unless you constantly smoke over it.
If anything I think it will lighten up a bit. Mine has been uncased for over 2 years and I've not noticing anything much. It does have a lighter undercoat on it.

Just curious here, If one were to buy a NOS 2008 American standard that had been on display for that time, would the price be expected to be similar to a new 2011?

Perhaps.

Hanging on the wall on display isn't exactly the same as been kept in the box and case new.
They would be stupid to keep it year after year and not try to sell it for any kind of profit.