So if I am reading correctly, baby is getting no liquids other than expessed milk, which he is now not drinking.
At 8 1/2 mo, I believe he should be getting milk before meals, but I remember my kids doing this too.
No, milk in foods do not count towards fluid intake. At 8 1/2 mo, he shouldn't be drinking any water, and no more than 2 oz of juice in a day, so all the rest of that needs to be milk. (milk in foods does count towards calcium requirements, but not towards fluid intake) If he starts showing signs of dehydration, take him to the doc immediately. (not peeing 4x a day, skin looking funny, soft spot sunken, etc)
He should get over fighting about it in just a few days, but until then, try feeding when he's asleep. Rub the nipple on his mouth once he's already passed out, or drowsy, and he should take it. I know it can be scary, just keep offering the milk. I had a nursing strike with my son, where he would only drink while asleep, for almost 2 full months, but that's supposed to be out of the ordinary, to fight it for so long.
And a baby will not voluntarily wean themselves before a year old, regardless of what you read. If they do, it's because someone was making other foods more appealing, which is not why we breastfeed in the first place. ;)