Shp edit question

[PatG]

Three questions. I have dug through the archives and the old yahoo list without success.

1) Is there a minimum and maximum size for icons?

2) What is the scale of the individual bmps used to generate the shp files? - how many inches/millimetres per pixel?

3) Is turret placement determined by game code or some other factor? - If other how do you set where a turret sits in relation to the underlying "chassis".

Thanks.