For your first question, there's a designation to get rid of ramps. I think it's d -> z. Or maybe d -> x?
I see a stockpile with seven rocks in it and several dozen chunks of wall that need to be built. You need to understand that when you initially designate a wall to be built, the materials you select aren't generalized. You're actually selecting specific stones, and those stones are immediately marked as being part of the construction. Once they're marked, they won't be moved except by the mason, and won't be used for anything else.
This means that if you have a stockpile of 7 rocks and try to construct a wall of 10 spaces nearby, all seven rocks will be immediately designated for use, as will 3 distant rocks. Those three distant rocks won't be moved to the stockpile because they're marked for use by someone else. If you then designate another 10-space wall, 10 more distant rocks will be marked for use, because the 7 in the stockpile are already taken. So on and so forth.
Dwarves always work on the most recently designated construction project, so the first one you set up (the one actually using the stockpiled rocks) will wait until the end, while the Dwarves busy themselves with the most recent one (which necessarily uses the most distant rocks.)
Once you understand these mechanics, the obvious solution is to make sure that the stockpile is full before you actually set up the projects. That way, all of the marked stones will be the stockpile ones.
You should also strongly consider putting a mason shop next to the stockpile and having a mason turn the rocks into blocks. Rocks become blocks at a 1:4 ratio, greatly multiplying the available materials. Blocks are also much lighter to carry, which speeds up the construction process.