Noob questions

Hi everyone, i am about to buy my first beys but i am enjoying studying a bit first.

I have a few questions:

• why would i ever use a taller bey? What could ever be an advantage in having a frail center of mass and more vulnerable ratchet?
• why would i ever use a 2/3/4/5 edges ratchet? Generally speaking why would i ever use a ratchet thats not a 0 or 7/8/9?
• why would i use a bit thats not "the best" at its specific category? I figured one single bit can statistically perform as a general best in its category, regardless of the specific blade and ratchet used

Of course I'm talking about being competitive and recognize anyone can use any combo on a for-fun basis.

Thanks to anyone for reading and possibly helping