Is there a detailed document describing how the price formulas work ?

I see snippets used in the system and in the documentation for Catalook but there isn't a detailed version.

I'm trying to add a product and add a flat rate (processing fee) to it.

I tried adding it as a component, but based on the quantity it is multiplying the processing fee.

Technically that is correct, but I need a way to do a flat processing rate added to the order.

Also, I have a product that has several options, based on the selected option I want to add that associated price.  For example, I have a product that uses ink for printing.  If the user wants to have a regular ink the cost is $50, if they want to use a special shiny ink the cost is and additional $100.

I think I should be able to set this with a pricing rule somewhere, I just don't have an example how.

Help please !