Well all games start out that way. Generally have room/time for 3-5 cities. From there:
Tall = Use excess happiness to keep growing taller
Wide = Use excess happiness to settle additional cities or hold onto conquered cities
Tall = Use excess happiness to keep growing taller
Wide = Use excess happiness to settle additional cities or hold onto conquered cities
Yes.
Of course, if you are playing a Duel map with 5 AI civs, it's both tall and wide (twide?), for that specific map set-up.
Vocabulary matters less than what it means for game play. Tall implies focus on greater population growth, with (usually) Tradition and running lots of specialists.