Aw, Jesus. Where do I even start?
Let’s start with these comments, left by an incredibly smart and helpful reader is way smarter than I’ll ever hope to smart:
You need to install a line of temporary shoring to support the roof TODAY. Support the “beam” (it might be a hollow box) in line with the current posts. jack posts between each post (with a plate on top), sitting on a double 2×12 plate, secured top and bottom. Get your roof properly supported and then you can deal with the deck framing.
I’d ditch the stone. I’d pour a sonotube 6″ above grade and run 4X4 pressure treated posts all the way up. (you can hack your round columns in half to hide the 4X4’s) Then build out, and trim base of the the posts to suit your house.
Something like this: