I have used the bassinet in C on the 747. If you are flying back from HKG directly to the US, then it will be a 747.

If I were you, I'd pick the middle seats in ROW 25 (first choice) and ROW 26 (second choice). These two rows have tons of leg rooms to fit a bassinet on the floor. My wife and I traveled with our daughter several times over the Pacific when she was an infant. I also believe the bassinet may be too small to fit a 13-month old baby. When my daughter was about ten-month old, she out grew the bassinet, and we ended up using 3 pillows (one to place her head on, the other two were placed on either side of her body to keep her stable. A couple of layers of blankets were placed beneath her body to make the surface a little softer to sleep on, and then we wrapped her in a blanket. You can order baby food, diapers and formula (included in the price of infant fare).