Sometimes, the warning light indicator (the exclamation point) flashes and the engine acts weird and I can hear a strange sound but then it goes away after two seconds or so
Does anyone know what this is?
Also, I have a rattling noise in the back seat...do you know what I need to tell a service advisor? What causes this noise?

 

this is the electronic stability control. It means your rear tires are slipping from too much power and the traction control is stopping the spinning. Completely normal. You can turn this off with the button underneath the emergency stop light on the dash, labeled ESP (electronic stability program)

 

Don't turn it off unless you want to total your car though.

 

ahhhh...that's why it slows down...
This happens on winding roads...
the car slows down and sounds like the engine is gonna die or the car would stop
so it's because of the ESC
also when I accelerate after stopping...the warning indicator light flashes
is it because the rear tires are spinning?

 

I would like to respectfully suggest that you read the freaking manual.

 

Ok, either you are driving really, really hard without thinking about it or your ESC is kicking in early. I rarely see ESC and when I do, was expecting it as I was planning on comming out of a corner pretty hard, etc.
How often are you seeing this?

 

I've only seen my ESP light come on on really icy/slippery roads. Never had it come on when I'm using the full powerband on my car or when I'm cornering hard. Either you are driving normal in icy conditions or you are seriously pinning your throttle down every light and throwing it around like a rag doll on the streets. Or you are not used to a manual and are engaging the clutch at higher RPM's causing slip. Either way, read the manual