Setup adjustments

[printbus]

I can confirm the extruder is retracting

Interesting.

The photo is of a direct-drive extruder. There's no gear reduction between the motor shaft and the filament pulley/gear. The filament drive motor is at the extruder, so it is not a Bowden style setup. 4.5mm retraction length seems like a lot for a non-Bowden, but I doubt that's your problem.

The cooling airflow percentage doesn't mean much from one type of printer to another - it's so dependent on the nature of the fan/blower and shroud. As long as the hot end can maintain temperature, you should be able to increase the airflow.

That V6 block is a pretty complex print to be starting with. It may be worth finding some simpler (and smaller) objects to experiment with while figuring out what all the settings do. Everyone has their favorite benchmark models to use. Benchy is a common one: http://www.thingiverse.com/thing:763622, as is the Maker Faire robot: http://www.thingiverse.com/thing:40212. These are small and quick to print.

To make it easier for others to help, let's start with more info. Give us more insight into what you have for a printer. There are possibly a thousand variations on a Prusa i3. If you bought it somewhere, tell us what brand it is or where you bought it. Is it running Marlin for firmware or something else? You're presumably using Cura for the slicer, but give us a more detailed run down on your settings than we have so far.