For most airlines and airports a qr code on a phone is fine. I’ve not seen one require paper tickets in years.
Seat wise. Middle seats are the worst option. A window seat gets you a little more space, with only 1 person beside you. An aisle seat gives you the option to stretch your legs, or get stuff from your bag, without disturbing anyone. The middle seat has you stuck in the middle, fighting for space on both armrests.
Location wise. I actually prefer being in the middle. The plane pivots on the wings. This motion gets more pronounced as you move forwards or backwards from the centre. This is at the cost of being one of the last off the plane.
It’s likely a bit late now, but I would definitely suggest getting some noise cancelling headphones. They are a godsend on a longer flight. They both reduce background noise, and let you both listen to music, audiobooks or podcasts on your phone, or plug them into the entertainment centre on longer flights. The provided headphones aren’t the most comfortable.