The cots are for smaller babies - and they have a downside as every time there's turbulence you have to take them out and strap them in with you.
My recommendations are take all the snacks, pack spare clean clothes for the toddler and you, more wipes and nappies than you think you'll need, squishy travel pillow so the seat sides can be made comfy, zip lock bags (handy to find stuff in, plus put dirty stuff in and seal it up)
Take a big rucksack as hand luggage so you have both hands free, and if you take a pushchair, get a buggy bag for it, so it keeps it together and relatively clean in the hold. She can also take the push chair and gate check it before she gets on - key if you want to maneuver a noncompliant toddler round the airport!
Order a kids meal and get something like a veggie / special meal for the adult - this means you get fed first (plus the kids meal usually has snacks / chocolate in it which my DS doesn't usually eat so I get it
)
Take a ziplock for carry on with medication for toddler and her - I always carry kids calpol and antihistamine, and for me some painkillers
Be warned about altitude - ime everything I have opened (water bottles, milk, drinks, nappy lotion etc) has spurted out at speed due to the altitude - bit embarrassing if you hit the guy 4 seats down...
When she gets on, ask the stewards which toilet has the baby change in it - its usually one that's marginally bigger than the rest, worth scoping out first tho, before she needs it!
Bulkhead seats are often offered to families / people with kids but I refuse them as they don't have seat pockets / seats to stash stuff under and I can't be arsed getting up and down into the overhead locker all the time
We have a kids amazon fire and noise cancelling headphones for DS - better than the airplane in flight entertainment system as he got really freaked out by hearing the pilot announcements all the time, plus they were loud.