I dont have much time this morning so I need a few more questions answered before I post a closer to correct answer.
When you say sloped do you mean the walls or the floors?I'm guessing floors?
When you take the column out is there more bounce in the floor?
Where are the nail pops mostly, on the interior walls or the exterior walls?
These posts you are talking about are screw type, Are they grey?
If so they are most likely only a temporary post desighned to crank up the house as it setlles. Sounds like no one came back to change them outat the end of the year.
These are No good in a fire!!
Keep digging to see if there is a footer.
Post me back with your answers and anything else,
Glad to help.