M.P.
Babies will eat as much as they need if the milk/food is provided. Also 2 oz. is not aimportant. His weight will fluctuate depending on the time of day, whether or not he just ate, peed or pooped. All babies and children's and adult's weight varies.
My advice is to relax and not pay attention to the way he is eating for now. Also, I recommend that you feed him out "in the open." Looking away to see someone/something is natural. We all do that. Let him look and he'll come back to the breast. Biting is not OK. I've not erxperienced that and so will leave advice on that to other mothers.
I suggest that he will do better if you approach the nursing in a sort of ho hum way. He'll eat when he's hungry. Perhaps because the 2 of you are in a routine that is not working, a change in routine may make it worse at first. He will nurse better once he gets used to the new routine.
If the mother is tense/anxious the baby will be too. That could cause him to pull away from the breast. Because he's sociable now
being taken out of the way into a quiet room may also be affecting how much he nurses. Perhaps he wants to get back to where the action is. I'd start by going into a quiet area away from the action but still have some noise; perhaps from a TV, radio or disc/tape player. If the other kids want to come in let them. Tell them they have to be quiet. They can talk or rub baby's head. My granddaughter would sing to her little brother.
I think 5 months is too early to start on any other solid food than rice cereal. At this age a couple of teaspoons is normal.
The reason we hold off on feeding solids is to reduce the chance of getting food allergies. As you said, milk is still the primary source of nutrition.
Try making how much he eats or drinks unimportant for a couple of weeks and see what happens. And lighten up on what is going on around him.