The guidance for 1yr is 12 - 20 oz per day including dairy solids. So if you want to keep the morning and evening milks that's fine, I'm assuming the evening one is about 6oz too. So that would cover his minimum milk intake. Anything else (butter, cheese, yoghurt etc) used in cooking or given in a sippy cup would be adding up towards the higher end of the guidance.
It's also advised to move away from the bottles at 1yr, but many people choose to keep them longer. I think it would be advisable to move the sippy onto a regular non-valved sippy spout though. It usually take time for them to learn how to use them and they aren't going to move on just on their own, it takes practice.
Yes you would replace the formula to cow's milk in the same number of oz.