front and rear fog light placement

If a single rear one - it goes on the driver's side. You have several option on front.  The front bumper can be used to mount where its wider on top on either side of where the nose juts out (see my Avatar).  There are OEM (and replica) mounts that clamp to the front bumper brackets (see below).  Later C model 356 placed the fog light below the bumper (which is much more effective).  Cory's car has them frenched into the fender cowl on either side of the hood.  

If you go to this site:

http://www.intermeccanica.us/availablecars.html

and scroll down to the black speedster with white wheels, you will see where the front lights are located, and also where the rear red 'safety' light is.  This might give you some ideas.

When I wastrying to figure out where to put mine I looked at every photo I could find of old Porsches with driving lights and I arrived at the conclusion that it comes down to whether you want a traditional or outlaw look. Traditional seems to be pretty clear, mount em to the bumper evenly spaced inboard or outboard of where the bumper guards are or would be, assuming yor going with a pair. I think Wolfgang is right about a single going on the drivers side.

Outlaw seems to be more body mount, obviously so if the bumpers are shaved off.

Just seems to be a matter of taste once you go outlaw or 60's racer boy look.

If mounting to fiberglass be sure to seal the hole edges and put big stainless steel washers on either side. 

Greg:

What do you seal the hole edges with, epoxy, or what?

If in a wheel well where it gets constantly wet I'd use fiberglass epoxy resin.  For fittings epoxy, fingernail polish or Rustoleum/model paint just something to seal visible fiber strands. Silicon would work too. 

Thanks' makes good sense.