1) If PML says they are waiting and intend to import the Euro6 2GT, then yes, I would say worth waiting if your priority will be lower running fuel cost due to high mileage. Then again, you have to wait and see on how high/low CEVS will be penalized on the new Euro6 2GT and you can make your informed decisions then.
2) Current 216d GTs are doing anywhere between 12km/l (around 80-90% City driving) to even 20+km/l for those who do around 80-90% expressways.
3) Well, its warranty now has been upgraded to 5yrs/200k ... so that helps in terms of plunging for a Beemer. Like many Contis, in general, they are a tad more "sensitive" in comparison to their Jap-counterparts. Otherwise, they are lovely to drive and lives up to the quality and expectations of the badge.
4) Meaningful in comparison to ...? Depends on what you are looking for really. It's a 5+2 compact MPV and shouldn't be seen in comparison at the same level as Toyota Estima, Honda Odyssey or even the VW Sharan. If u wanna compare the 3rd row, It's slightly more spacious than the Grand Scenic but prob abt the same as Touran/Grand Picasso although I would put the GP slightly more spacious prob due to the seat config design. Go chk out these 5+2 MPVs out and I guess you'll make your decision thereafter base on your needs.
Happy shopping!