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railgun caps / (high value capacitors > 1 fared)


This is kinda off the subject so forgive me, but it does have some
capacitor construction questions.Reply directly to me at 
<mailto:corr-at-enid-dot-com>corr-at-enid-dot-com if you can help.
  
I'm getting ready to experiment with coilguns and railguns now, as 
apposed to Tesla Coils.  It has come to my attention that no matter
which setup I decide to make, based on various factors, I am going
to need extremely high current pulses through the coils / rails.  
  
Therefore I need some information :
  
1.  Is there any way to build a homemade capacitor with HIGH values,
     aside from the fact that I could role a poly cap a mile long?  The
voltage
     only needs to be around 200VDC to 300VDC.  Are there any dielectrics
     that have high enough voltage rating with good capacitance?
  
2.  For those who have built railguns, what type of "track lubrication"
would you
     recommend to prevent contact welding to the track?  I have heard
graphite poweder
     works well, but would have the disadvantage of needing to be applied
again and again.
  
3.  For those of you who have knowledge of coilsguns, what gauge of wire
and how many 
     turns would you recommend for each coil, assuming the discharge
through them is
     at least 200VDC at 1 fared for each coil.  I was thinking around 6 or
7 turns of #6 would
     be good for a high powered pulse.
  
4.  If I was to build a coilgun, what type of "barrel" would be best.  I
realize I need one that does
     not store a magnetic "charge" after the coil around it is
un-energized.  This would 
     cause a backwards pull after the projectile has left the first coil,
slowing it down too much.
  
5.  I have 500VA transformer with several taps.  I can get 60v, 120v, 220v,
240v, 360v, 480v, 
     and 600v out of it, slightly higher after adding my 35amp DC recifier.
 I'm guessing this 
     would be good for charging up the capacitor bank, but upon doing so,
what would you 
     recommend I use as a shunt resistor.  The caps will pull quite a surge
as soon as the 
     circuit begins to charge.  I was thinking a couple of 500ohm 100watt
resistors in parrallel.
     Would this be too high?
  
Any other help is as always appreciated.
Sorry for the long message!
  
Thanks! 
-Jeff