How do you take out the air in the radiator coolant after taking out all the water?

What could these hoses be? They are mounted to the body of the van and are further back from the engine itself.

I am running low on coolant in the engine now, can I fill it up with a different coolant I have in my garage? I have a Dodge Grand Caravan. Thanks.

How do you remove the inner coolant pipe on the outlet. I’ve removed the 2 bolts from the bell housing and I can wiggle it, it’s got plenty of lateral movment, but I can’t pull it out. Also, would Chilton’s or Haynes books address this specific issue? I’m not sure how detailed those books are. Thanks.