i want to change the size of certain nodes or use different icons in the node graph

nodes like camera or lights are far to big for my taste
as i understand you can only read the screenwidth with python, but i\'d like to
set a new (default-)value

if that is not possible, then maybe i can use a different icon for those nodes
it would be cool to know, were these icons are stored and how to change them

maybe someone has an idea of how to do this ...
thanks