M.M.
Cereal in the bottle is a choking hazard and it doesn't help with sleeping through the night. If you want to feed cereal, do so from a spoon. If she won't take a spoon, then she's not ready for the cereal.
Most kids tend to sleep better at 2-3 months than they do at 5-6. They're about to start hitting a bunch of developmental milestones. That's also a common time to start teething. There's nothing you can do to make her sleep through the night. You can make it less appealing for her to be up. Don't turn on any lights, don't play. Just do whatever it is that you do to put her to sleep. Make night time boring.