One kit is the parts needed to assemble the extruder and you will source your own electronics. The other kit is the electronics and you have to print the parts.
The filament size will be either 1.75mm or 3mm (you are choosing 1.75mm) and the spool weight is at least 2.2 lbs. We are known to throw in the extra 1/3 lb since we do our batches in 5lb quantities, winding two spools at a time.
Yes, the guys have decided they will set up shop and sell these. But, the kits will start at $499 and the assembled extruders will start at $999.
Don't see the answer to your question? Ask the project creator directly.