For crucible sizing I have been using this info from this data sheet on the Super Salamanders, I have found it very useful:
If I spent half a year building forms ... it would never get done.
Burner will probably be one of the two commercially available waste oil siphon burners, just for ease and to reduce the dinking around (hopefully). The plan is to keep my eyes out for some tube or pipe, for the tuyere, at the scrap yard this weekend.
Looking at MyfordBoy's blog yesterday, he has the dimensions for his furnace on there (I had not looked at the drawing before, I was not expecting it to be in inches :-) ). My measurements above are very close to his.
OK so based on everyone's input, it looks like I have done enough base homework and am at least headed down a track to success. More questions and probably pics to follow.