If I understand this correctly...the printer will extrude up to the coast point, at that point the extruder stops feeding filament but continues moving up to the stop point. At the stop point retraction will occur followed by the wipe which will continue along the perimeter.
So...blobs and strings that occur at the end of an extrusion are functions of retraction, coasting, and wiping. Blobs that occur at the start of an extrusion would be due to priming too much from Extra Restart Distance. Conversely if I am getting holes at the beginning of an extrusion layer then I am not getting enough priming and should increase the restart distance. Sound about right?