Help with print quality and or Slic3r settings

Check your Retraction Length and Speed settings under Slic3r Configuration (Printer Settings Tab - Extruder 1).

Try increasing the speed and length a bit and see how that works.

have you done a proper filament calibration?
as in measure the diameter of the filament in multiple locations with digital calipers (7 or more measurements over a couple of yards/meters) and calculated an average diameter for that roll?
the average diameter would then be entered into your slicing program - in Slic3r it would be on the filament settings tab > filament diameter

Set the extrusion multiplier to 1 and print a single wall calibration box (20mm x 20mm x min of 10mm high - height doesn't matter too much as you will be stopping it before it prints fully anyway) with these settings;
perimeters - 1
top layers - 0
bottom layers - 2
infill - 0
on the print settings tab, under advanced - your default extrusion width should be set to 0.48 for the stock SD hotend (0.4 nozzle)
1st layer = 100% (or more, I use 100% and it works fine)
leave everything else at zeros for the default width

start the print, let it get 5-10mms high and kill the print.
remove the box and measure wall thickness on each wall (try to only get one or 2 layers for your measurement) with your calipers making a note of what the measurements are.
add them up and average. you are shooting for a wall thickness of 0.48mm - chances are the walls will be thicker than that for the first print in this calibration.

use the measured average to calculate what your extrusion multiplier should be set to
example:
measured wall = 0.52 averaged
formula: 0.48 (desired size)/0.52 (measured size)=0.923....
0.923 is what you enter into the extrusion multiplier box - save the profile, re-slice your box and print again - measure and average and make adjustments as needed to the extrusion multiplier to obtain a wall thickness of 0.48

additionally - every roll of filament will be different - this calibration should be done for each new roll you run.
You can save a new profile for each roll if you change colors frequently like i do (I have roughly 30 rolls, all different colors/materials) just be sure to name it appropriately so you know what profile goes with what roll.

OK...looks like over-extruding to me!  Your Retraction settings should be fine.

Do what heartless said above!

I was just about to post something like this. So I do

for what it is worth, my retraction settings for the stock SD4 hotend...

Length: 1.5
Lift Z: 0
Speed: 30
Extra length on restart: 0
minimum travel after retraction: 2
retract on layer change: checked
wipe while retracting: unchecked

these seem to work well for me, your mileage may vary

I made this on thingiverse:

http://www.thingiverse.com/madfalcon81/designs

Post a picture.
As for vibrations, does it vibrate on the y when it's not printing?

belts should be snug - not too loose, but not too tight. if they are too loose you may be getting misalignment of the carriages and that is where your "grinding" is coming from - or the belts could be jumping teeth, which can also lead to misalignment, and damaged belts.

snug up the belts, then loosen the set screws on the rear pulleys - work the carriages back and forth until everything moves smoothly and is properly aligned, then tighten the set screws.

with the carriages all the way back you should just be able to pinch the 2 sides of the belt together midway between carriage and idler pulley - there should be just a little resistance - and both sides need to be the same tension.