I LOVE our Supernova Guns. We saved over 20% on our Matte clear usage on our production line just from changing from a Sata 4000 1.3 HVLP to a Iwata Supernova 1.4. (Yes, even w a larger tip). I have to chalk it up to transfer efficiency somehow
The basic process is prep, paint, dip, topcoat. The topcoat is what protects your dip and baking/curing your topcoat should only be done per the recommendations of the topcoat manufacturer. It's not going to increase the overall durability of the topcoat, but will make it get hard/able to be handled more quickly. In general, 2k Urethane topcoats (2k meaning 2 part, mixed with hardener) can take up to a few weeks to fully cross-link. Heating/baking can help speed this along and make it quicker to be able to handle/package, but often times there is still a slow curing process that must take place.
There are various topcoats that are extremely hard (but you'll pay for it), and even powder coat clear that is baked on. Too many options to list here. All depends on your experience and ability to apply it and how deep your wallet is.
On our automated system, I over estimate at 2oz per meter. But that is with me running thousands of the same parts in the same film, so I can track it accurately. You will have so much variability between HVLP guns and personal application technique that the 2oz mentioned is all but useless. LOL. Best advice? Order a gallon, reorder when it gets low.