The popping on decel is pretty normal. I get a lot of gurgling especially in 1st & 2nd gear (6MT). Sometimes you can get a pop when downshifting to - also normal.
The idling & starting definitely sounds like an issue, and fuel economy seems high (however very dependent on driving condition).
A quick check would be to pull all the spark plugs and check condition. they should all look pretty equal. You might have a bad coil which is a common issue on older 1.6T's.
Definitely bring up your issues with a dealer, and get some audio/video of what you are noticing. Dealers tend to think 'there's no issue' if the scanner comes up clean (terrible dealership mentality IMO).
With the car being so new, definitely bring it in for warranty.