Pretty ugly surface remains after using support ramp. Are my slicer settings correct?
I'm not terribly familiar with slic3r, but it looks like you have a setting (possibly a default one) to slow down on printing overhangs. This was a popular "feature" in slicing software (Cura has it I know) but it's exactly the opposite of what you should be doing. When slowing down to print an overhang, the pressure in the nozzle forces the material to keep coming out at the same rate it was coming out until it subsides, and you end up with a big hanging glob of ooze like in your photo.

If your printer firmware has linear-advance/pressure-advance functionality, this can mostly be eliminated. But if not (most stock firmware), you need to maintain full speed on overhangs, and might even need to turn up your acceleration limits so that you don't get a significant slowdown just by decelerating to go around the corner.