Since the vertices are $(\pm 3,0)$, the hyperbola is centered at the origin with horizontal transverse axis, so:
$$
\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1
$$
Given the vertices, $a = 3$ so:
$$
a^2 = 9
$$
Use the point $P(5,2)$:
$$
\frac{5^2}{9} - \frac{2^2}{b^2} = 1
$$
$$
\frac{25}{9} - \frac{4}{b^2} = 1
$$
$$
\frac{25}{9} - 1 = \frac{4}{b^2}
$$
$$
\frac{16}{9} = \frac{4}{b^2}
$$
$$
b^2 = \frac{9}{4}
$$
The standard equation becomes:
$$
\frac{x^2}{9} - \frac{y^2}{\frac{9}{4}} = 1
$$
Multiply through to simplify:
$$
x^2 - 4y^2 = 9
$$
Foci
$$
c^2 = a^2 + b^2 = 9 + \frac{9}{4} = \frac{45}{4}
$$
$$
c = \frac{3\sqrt{5}}{2}
$$
Thus the foci are:
$$
F\left(\frac{3\sqrt{5}}{2},\,0\right),\qquad F'\left(-\frac{3\sqrt{5}}{2},\,0\right)
$$
Asymptotes
General asymptote equation for a hyperbola centered at $(h,k)$:
$$
y - k = \pm \frac{b}{a}(x - h)
$$
Here $(h,k) = (0,0)$, $a = 3$, $b = \frac{3}{2}$:
$$
y = \pm \frac{b}{a}x = \pm \frac{\frac{3}{2}}{3}x
$$
$$
y = \pm \frac{1}{2}x
$$
Final Answers
Equation of hyperbola:
$$
\boxed{x^2 - 4y^2 = 9}
$$
Foci:
$$
\boxed{F\left(\frac{3\sqrt{5}}{2},0\right)},\quad
\boxed{F'\left(-\frac{3\sqrt{5}}{2},0\right)}
$$
Asymptotes:
$$
\boxed{y = \frac{1}{2}x},\qquad \boxed{y = -\frac{1}{2}x}
$$