(1) To prove: $$\sqrt{a+5} - \sqrt{a+3} > \sqrt{a+6} - \sqrt{a+4},$$ it suffices to prove: $$\sqrt{a+5} + \sqrt{a+4} > \sqrt{a+6} + \sqrt{a+3}.$$
It suffices to prove: $$(\sqrt{a+5} + \sqrt{a+4})^{2} > (\sqrt{a+6} + \sqrt{a+3})^{2}$$
That is to prove: $$2a + 9 + 2\sqrt{(a+5)(a+4)} > 2a + 9 + 2\sqrt{(a+6)(a+3)},$$
That is to prove: $$\sqrt{(a+5)(a+4)} > \sqrt{(a+6)(a+3)}$$
It suffices to prove: $(a+5)(a+4) > (a+6)(a+3)$, that is to prove: $20 > 18$, since the above statement is obviously true,
Therefore, the original inequality holds.

(2) Assume that $a$, $b$, and $c$ are all not greater than 0, i.e., $a \leq 0$, $b \leq 0$, $c \leq 0$, thus $a+b+c \leq 0$
However, $$a+b+c = (x^{2} - 2y + \frac{\pi}{2}) + (y^{2} - 2z + \frac{\pi}{3}) + (z^{2} - 2x + \frac{\pi}{6})$$
$$= (x^{2} - 2x) + (y^{2} - 2y) + (z^{2} - 2z) + \pi = (x-1)^{2} + (y-1)^{2} + (z-1)^{2} + \pi - 3$$
Therefore, $a+b+c > 0$, which contradicts the assumption that $a+b+c \leq 0$. Hence, the assumption is incorrect.
Thus, at least one of $a$, $b$, or $c$ is greater than $0$.

Therefore, the final answers are:
- For (1), the inequality $\sqrt{a+5} - \sqrt{a+3} > \sqrt{a+6} - \sqrt{a+4}$ holds.
- For (2), at least one of $a$, $b$, or $c$ is greater than $0$, which can be encapsulated as $\boxed{\text{At least one of } a, b, \text{ or } c \text{ is greater than } 0}$.