as for clearcoats. i use House of Color, it seems to be the most forgiving and lays out nice and i've not had problems w/ passenger seats putting indentions in the paint b/c it's not hard enough. but there are many great clearcoats out there.
flattend clear makes a different effect than a flattend single stage paint. it's got a milkiness to it. i think HOK and also Kustom shop has a flat clear already
here's another onr for you