is Caesars Palace circuit (INDY) the biggest flat oval?
& is it the only oval track with right turn?

It's not really an oval, and i don't think its the biggest either.

According to this track map its counter-clockwise so all the corners are left turns, not right
https://www.racingcircuits.info/north-america/usa/caesars-palace.html

Quote from nikopdr :

It's not really an oval, and i don't think its the biggest either. ...

this is the right turn

& which is the biggest flat oval u think?

I found this:
https://en.wikipedia.org/wiki/Aut%C3%B3dromo_Internacional_Nelson_Piquet

No info on the banking but it looks flat in videos.

Quote from Gutholz :

I found this...

It looks like very low angle but not flat?

Quote from scania :

this is the right turn

& which is the biggest flat oval u think?

I would probably say the mexican gp track has the largest fully flat oval at 1 mile long. They seem to be using the stadium section for nascar, too but there is also an oval layout raced counter clockwise

https://www.youtube.com/watch?v=NxCCuPnIbsU

Quote from nikopdr :

I would probably say the mexican gp track has the largest fully flat oval at 1...

oh, I forgot this