Welcome to the world of solids!
1- how much should I be giving him in one sitting? Feed him until he's finished and doesn't want more?
It really varies quite a bit...an average "meal" for a beginning solids eater is anywhere from 1 tsp to 1 tbsp. It's not always a good idea to feed solids until he's full, unless you're certain it isn't decreasing his interest in the next nursing session. Keep an eye on how long he nurses as you introduce solids to be sure he doesn't fill up on solids and breastmilk is still his main source of nutrition.
2- I know that I need to wait 1 1/2-2 weeks before introducing the next food, but when he starts to another food do I feed him the new food and the rice as well?
This is purely up to you and your DS. Some babies like the new food to be mixed with something familiar, others don't care. When Tyler was new to solids, we did cereal until we added the 2nd meal (lunch). Then we moved the cereal to lunch and used breakfast for introducing new foods. That's just what worked for us.
3- Once I mix the rice cereal (with BF) I assume that whatever he doesn't eat needs to be thrown away and not reused at the next feeding?
That's correct. And anytime a spoon that's been in his mouth goes back into the jar, you shouldn't reuse that jar of food. Enzymes from his saliva will cause the food to spoil quickly.
4- Is the general idea to feed solids after I BF? Or in between feedings?
This is also up to you and your DS. I always did solids about 1 hr after BF. That helped me make sure that Tyler didn't fill up on solids first, but he'd gotten hungry enough to have a little appetite. That's not an issue for some babies, and some eat solids before BF or immediately after.
Hope that answers your questions! Have fun!
