DDK - Die Deutschen Klassiker

I am just sanding back the gel coat finish in prep for painting and have a few marks/nicks/pin holes that need repairing. Whats the best stuff to do this with?

Also how corse should I leave the sanded surface? Will I need to go over the whole car with some wet and dry after using an orbital to take off the shiny stuff?

I also have a hole in the door (!) but will fill this with fibreglass resin.

thanks

I used 80 grit and then sprayed 3 litres of spray filler (u-pol reface) before guide coating and then used primer/basecoat/clear.
have a look here
http://www.550spyder.pwp.blueyonder.co.uk/paintwork.htm
Stephen