Well then again, no, I would remove everything from the room and then seal off the door to the room with heavy plastic and cover the floor with tarps to protect it and collect the mess.
I would tear down the ceiling because as you have stated, there is a bow in it already. I would not add any additional weight to a bowed ceiling and I would want to get rid of the bow. Nothing personal, I just don't like bows. A bow tells me that something is not being supported.
I would not replace the ceiling because you put a new roof on, I would replace the ceiling because it needs to be replaced.
As far as removing the 100 year old baseboards, yes, I believe in order to do the job right, you will have to do this. Lucky for you, you won't have to use a 100 year old carpenter to do this!
I would use a middle age person who has learned that if you want to anything right, you need to slow down and be gentle. (Kids these days, always in a hurry!)
Anyway, I believe you will need an all around handy-person who can demonstrate he/she has the knowlege to perform the tasks you want done.