The snare is the heart of any kit, and more experienced players soon learn that having a single snare is a bit like having only one golf club–different snares for different situations.
Tuning drums is both an art and a science, and striking the right balance depends on the player and the situation.
Now, I don’t subscribe to the “singing” method, but if it works for you, go for it. Ultimately, if it’s your kit, and you like the sound, then that’s all that matters–the rest is the sound guy’s problem…
Heads matter, too, and some heads just sound better on different drums, depending on material, size, etc. A lot of it is, again, just personal preference, but I’ve found that Evans heads tend to tune easier, but some Remo heads sound better (to me at least) tuned lower, especially on the big toms, like 16″ or 18″ floors. The best way to figure it out is to try everything and see what works for you.