Interesting. I'd never heard of this stuff and your post wasn't particularly enlightening but I googled a bit about them.
It sounds like there are pluses and minuses, with them being regarded as better looking than other metallics but requiring alcohol, dedicated brushes, etc and their gold in particular having problems irretrievably drying up/clumping (sometimes coming like that when bought).
I'm not sure about the base coat thing.
One article I came across said:
"7. What base coat?
Two or three layers of any Liquid Gold colours will cover well a black primer undercoat but I suggest you start from a layer of colour of similar hue, like a red-brown for Copper / Red Gold or a more yellow one for the other Gold colours. However, a black base coat will work well for Silver"