another thing to note about electrolytic capacitors: if overloaded they not only fail but can explode! I learned that one permanently, down in the basement waaaay back when... if the leads are both at one end and soldered in, the can goes flying.
and Cxrazy, yes it's ok to mix different voltage rated capacitors. The voltage rating is just the maximum working voltage, and does not affect the circuit (except if the capacitor starts to fail).