Yeah, old post by the time I joined this, but I think your second point doesn't make any sense.
"Japanese dragons are mostly connected with Sea, Wind, Storms in Mythology. So a fire breathing dragon would be weird in point of a Japanese view"
You are thinking of Asian dragons, not European dragons. Asian dragons are more serpent-like, like Gyarados and Dragonair, while European Dragons or more like dinosaurs and breathe fire, like Salamence and Dragonite. To say that GameFreak only took inspiration from Asian sources is really closed minded. If so, Sandshrew's Japanese name wouldn't literally be "Sand".