1. Definitely Qatar given the equipment used on those routes. The 9 abreast 77W from EK will be a lot more cramped than the 788 on QR.

2. DXB is more interesting since it's a lot bigger thus it has more to do.

3. The 787 Y seats on QR give you ample pitch and is the best your going to get between those two carriers.

4. Not sure about this one, but most likely yes.

5. This really doesn't matter, they are Y meals, so probably very similar.