i use simplify3d. i dont know if the coast setting translates over to any of the other slicers. as for the filament, the fact that it moves 20mm when you have it set to move 20mm is right and that is generally set in the firmware but it can still put out too much on the model it printing. thats all adjusted buy setting your filament diameter and extrusion multiplier. your torture test in the middle does look much better though. it could have been just from the heat. you just need to bump up your retraction. you can see the strings still there. bump your multiplier down a little at a time as well.