Hello Cinnamon. I'll try to answer all of your questions, hopefully 
Yes you can ff in the day and bf at night.
The current minimum for formula from 6 to 12 months is 20floz. However, as you will also be bfing, I'm not sure on the quantities. A BFC should be able to advise you on the this, do you have the Bfing Helpline numbers?
As for the quantities I'm not sure as I never measured what I gave them 
According to the NHS guidelines on starting solids babies should move to 3 meals a day between 8 and 9 months, so I'd stick with just the one meal for now.
If you wish to switch to formula, I think the current advice is to swap one feed every 2 weeks. This is to reduce your risk of mastitis and to give time for baby to adjust to the new quantities.
It's also advised to give solids roughly an hour after their milk feed. This is to make sure that baby doesn't drop their milk too quickly. If very important that baby drinks their milk at this age, solids are just really a little add on.
With all of this in mind, it might be worth swapping the early morning bf, at about 6 or 7 am for a bottle of formula and then offering breakfast an hour later. Do that for a couple of weeks and then swap another bf for formula. How does that sound?