Quick simple capacitor questions

Hi. I have a coil and a bunch of solenoids. Ref: http://www.picbasic.co.uk/forum/showthread.php?t=8432

What happens when none of the solenoids are turned on? That coil will be charging the capacitor but it will be putting 55 volts and god knows how many amps into it. Will it be fine to do that for maybe a day with no load on it? Obviously the capacitor is rated at more than 55V.

Another simple one. Does it matter what type of capacitor i use? I have some pretty big ones but they are non polarised. Does that make a difference or does it just mean they can be connected either way round. Would it be better to use a polarised one? (its DC by the way)

And finally, when i connect the capacitor my multimeter says the coil is outputting upto 90 volts instead of its normal 55. Whats happening there?