From my experience be careful mixing laquers and enamels. Laquer is a "hot" base, enamel tends to be "cooler" or less aggressive, slower drying.
Basic rule I live by is never top enamel with a laquer, other way around 'should' be safe, but without experimentation I'd still recommend a gloss clear acrylic layer before applying any wash.
As for washes, I almost always use heavily thinned enamel or artists oil paints on top of an acrylic clear gloss. Hope this helps.