S.,
Sleeping through the night is one of those touchy subjects where everyone has an opinion. What you can or will do about it is going to depend a lot on your beliefs as a parent and what works best for your family.
We are very much and Attachment Parenting Family and do not believe in letting a child Cry It Out. My Dd is, and always has been, fed on demand. We also subscribe to the belief that before 1 year, some babies NEED to be fed at night. Dd was up every 1.5 to 3 hours at night from 6 months to 15 months when we night weaned. It was an incredibly simple process to introduce the idea of no food/drink at night because we were both ready for this step and she was emotionally and physically mature enough to handle the change. She also better understood what I was asking of her.
Please do not add cereal to his bottle without the recommendation of his doctor and strict medical supervision. Cereal in the bottle can be a choking hazard and can be dangerous. My daughter actually slept better from 3-6 months, before we introduced solids.
Is it a problem for you that he's still waking at night? One night in particular stand out for me when I was desperately rocking and nursing my daughter at 3 am, pleading with her to go back to sleep and thinking to myself how much I hated nursing in that moment and how resentful I was. But in the end, I am thankful every day that we stuck with it and at 2 years old, she sleeps through the night beautifully. If she does wake up, I don't even get out of bed, I just have to say "Taylor, it's the middle of the night, go back to sleep" and she puts herself right back down. Of course, it helps that her crib is in our room - but we're looking forward to moving and everyone having their own room.
S.