These sites are definitely helpful, even if you don't understand spanish too well.
The suggested wiring seems a bit heavy though, 20A, 4 mm2 or 15A, 2.5 mm2 seems quite heavy for standard circuits.
4 MCbs seems a bit few for an entire villa, but it reminds me of the standard panel here in Austria. 2 circuits (6A each) wasn't all that uncommon for appartments of 100m2, nowadays this is usually upgraded to 2 or 3 13A circuits.
The suggested circuit layout with junction boxes above each receptacle/switch seems nice, it's the way installations used to be done here as well, makes for a very logic installation. I don't like wires strung across or run inside ceilings or wires daisy-chained from one receptacle to the next like in the US. This way it's easier to guess where the wires run, and an average trained homeowner will run less risk of drilling or nailing into cables.
Obviously the Spanish use wirenuts or boxes with terminal strips.
