Questions about capacitors in DC
If it's fully charged there's no current. When not or partly charged there will be current if you apply a voltage to it. The current curve depends on how your voltage source is connected. If you supply a constant current the voltage will rise linearly, if you charge over a resistor it will rise exponentially. That's because the rising voltage will cause the voltage drop over the resistor to become smaller and smaller, and hence the current through it will also decrease. A lower current means that charging goes slower.  

  

How fast the capacitor charges depends on both the resistor's and the capacitor's value. The larger the resistor the slower the capacitor charges, and it also charges slower if the capacitance is greater. The exponential curve is said to have a time constant \$RC\$. After about \$5 \times RC\$ the capacitor is charged to 99%.  

9V. The capacitor's rating has nothing to do with it, that only determines how high a voltage you can apply. Just look at what voltage is available, and that's 9V. Just take care that the capacitor is fit for the supplied voltage. You can safely charge a 16V capacitor to 9V, but not to 25V.