If you're giving 9oz in the two bottles I don't really see why you need the milk intake to stay up the rest of the day. 18oz of milk plus a couple of servings of cheese (1oz is about 1"cube) or yoghurt (small pot 1oz) is plenty.
I do not think that 11am for snack and 12pm for lunch is too close together. I put both the mid morning and mid afternoon snacks at exactly the same time as the bottle had been. The snack is not a huge meal, just a little something to get through to lunch so LO is not waiting all the way from breakfast. A small piece of cheese or a small cracker, a few sultanas or a slice of apple say. And it needn't be a long time spent in the high chair, couple of mins. If you prefer you could set up snack sat on the floor. We were often at mum and baby groups for snack so it was either sitting on the floor or on my knee, or at a kiddie table with the other kids. 5 mins max.
Switching to cows milk from formula, I just switched in one go. He'd had cows milk in cooking so I knew there were no issues but he hadn't had it as a drink. tbh frank I switched at 11.5 months as I couldn’t' find our formula in any of the shops throughout our town and I didn't see the point in switching to a different formula (which could have caused issues itself) for the sake of 2 weeks. DS didn't bat an eye, but of course some LOs would like the switch to go a bit slower. I would just put cows milk in the bottle and see how it goes, if it's rejected you could pour 1oz into a formula bottle to begin a slower switch over.
You might find this thread interesting
morning bottle still needed?It covers a gentle wean of the BT bottle, I describe the way I did it and you can also follow Happy's successful wean of the BT bottle too.