on the question of lacquer as an extra protective layer, it is not recommended for the majority of waterborne enamels from the likes of Tikurrila, BM etc. Extra coats of the finish is more practical. It means one less product in the mix, one less guess about adhesion and compatability.
There are paint systems which specifically are formulated with a clear lacquer in mind. Annie Sloan have a clear lacquer to protect chalk paint. There are also commercial grade usually spray systems where the basecoat is sealed with a clear lacquer for extra double durability.
We tend to use the first brands mentioned for painting cabinets.