Re: 4 month old - rice cereal, how much milk in bottle etc.
Early solids introduction doesn't increase weight gain and doesn't make the baby sleep better. All it does is substitute a food that lacks the immune-protective qualities of human milk for breastmilk in the baby's diet. This is why the AAP's recommendation is to start introducing solids at 6 months, not 4. Sounds like you pediatrician probably hasn't been keeping up with the times in this area.
12 oz may be a little low for a 10 hour separation. But go with that and see what your baby likes- if he's satisfied with 12 oz, then there's nothing wrong with that. Whatever quantity of milk you end up using, the bottles should be around 2-4 oz and should be fed on demand rather than on a schedule.
Coolest thing my big girl said recently: "How can you tell the world is moving when you are standing on it?"
Coolest thing my little girl sang recently: "I love dat one-two pupples!"