For the last panel it looks pretty good, though trying to match the gradient might be a bit annoying. I'd say try to eyeball it with the gradient tool, experimenting with the opacity and a whole lot of Ctrl+Z. That's how I usually do it. Once you get the pattern right, redrawing the lines with the line tool will be easy. Just make a new layer, draw the lines, then scale down the opacity of that layer until the lines you draw more or less match the original ones.
In panel 4, the edits are a little more obvious. I've found that it's helpful to just copy a section from the raw layer and move it into position to cover up the text, then edit that as needed. The gradiented part between the actual grey pattern and the black is probably going to be your most annoying thing to replicate. Still, going to town with the clone brush is the way to go, I think. Just be careful to make sure you cover up any repeating patterns that shouldn't be there (like the little bit just above the necklace's chain on the right).
Speaking of the necklace, the brush is a little thick on it. Maybe go down to 1px and trace it once or twice instead of 3px?