JW's "Right-Step Matte Varnish" works. Use two thin coats as a barrier before adding traditional oils on top.
JW's "Right-Step Gloss Varnish" does NOT work. Do NOT use it.
As to the heat guns: I don't like them very much as it takes too long. Genesis suggests that a cheapo quartz heater works too (and you don't have to stand there and hold it).
Also, the drying oven is not that expensive and if you're going to be using Genesis, it might be worthwhile to purchase one. "Art Supplies Wholesale" in Beverly, MA has good Genesis paint prices. See:
http://www.allartsupplies.com/