Can't comment on Y, except that it's standard TG economy (no seat-back video), but I understand that the seats are quite good compared with other airlines. I usually fly C, and it's fine - seats not particularly comfortable (old, domestic-style C class seats), but space and service are ok.
In DXB - disregard whether the crew tell you to leave the aircraft or not. 50% of the time they tell you not to disembark, but 100% of the time (unless the flight has been delayed and you don't get to the gate) you can disembark and Dnata staff will always be waiting with the transit cards. Always leave the aircraft and stretch your legs. Take your boarding pass and passport with you. As you get off the plane, you will be given a plastic transit card in exchange for your BP.
After about an hour, the plane re-boards. And you're on your way to Kuwait.
The good thing about TG is that you don't have to risk missing a connection, or getting a lost bag, from transiting to a different plane in DXB.
If you get visas on arrival in Kuwait (or even if you are resident) I always recommend paying for the "Hala" meet-and-greet service, which you can email to get (
[email protected]) - just give them your name and flight details. I think it's 8KD to be met and whisked through immigration. I think it's about 3KD to pay for the visa if you need one.