If I may step in...
Cuando la noche apaga su voz = when the night turns out its voice = when night becomes silent
Por la boca muere el pez = the fish dies by its mouth = it opens its mouth too much (so swallows the hook) and dies = you talk too much and prove yourself what you realy are (and your're doomed!)
En eso eres el mejor = you're the best at that
un torero de salón= a loundge bullfighter = a guy who says he can perform wonders but does nothing
[You demonstrate?]: I'd say [you talk about]
Querer no es siempre poder = willing isn't always being able to