I agree with all of the above. The hybrid simply won't get you where you may want to go off-road. Suspension can be the difference between cleaning an obstacle and walking an obstacle, and your learning curve will be faster. Even if you are "just doing fire roads", you'll want a mtb bike. Some fire roads can be incredibly technical, steep, fast and rocky. You'll get beat to death without suspension and your traction will be better with it.

If you can afford it, get a mt bike with shocks that lock out for riding on the road. Also, you may want to use flat bars and bar ends. You will have more hand positions which can be critical on long road rides. They also give you more leverage on long hill climbs off-road.

If you are short, a flat handle bar may also give you a better riding position. Frequently, head tubes on smaller bikes are not as short as they could be so you can't get your bars low enough in relation to your saddle. If you are going to use your bike on the road, you'll probably want to do everything you can to give you a flatter position. A hybrid will give you the opposite of everything that you'll want for optimum riding.

Get slicks as narrow as possible and that can be pumped to a high PSI so that you can lower the rolling resistance on the pavement.

Let us know what you picked!